Polymerization with living characteristics

ABSTRACT

This invention concerns a free radical polymerization process, selected chain transfer agents employed in the process and polymers made thereby, in which the process comprises preparing polymer of general Formula (A) and Formula (B) comprising contacting: (i) a monomer selected from the group consisting of vinyl monomers (of structure CH 2 =CUV), maleic anhydride, N-alkylmaleimide, N-arylmaleimide, dialkyl fumarate and cyclopolymerizable monomers; (ii) a thiocarbonylthio compound selected from Formula (C) and Formula (D) having a chain transfer constant greater than about 0.1; and (iii) free radicals produced from a free radical source; the polymer of Formula (A) being made by contacting (i), (ii) C and (iii) and that of Formula (B) by contacting (i), (ii) D, and (iii); and (iv) controlling the polydispersity of the polymer being formed by varying the ratio of the number of molecules of (ii) to the number of molecules of (iii); wherein Q, R, U, V, Z, Z′, m, p and q am as defined in the text.

This is a Division of U.S. application Ser. No. 10/784,425, filed Feb.23, 2004, now U.S. Pat. No. 7,250,479.

U.S. application Ser. No. 10/784,425, filed Feb. 23, 2004 is a Divisionof U.S. application Ser. No. 09/762,833, filed Jan. 30, 2001, nowPENDING.

BACKGROUND OF THE INVENTION

This invention relates to a free radical polymerization process withcharacteristics of a living polymerization system in that it is capableof producing polymers of pre-determined molecular weight with narrowmolecular weight distribution (low polydispersity), and, by successivelyadding different monomers, can be used to make block polymers. Theprocess can be used to produce polymers of more complex architecture,including variously branched homo- and copolymers. The use of certainreagents in this process and the polymers produced thereby are alsoclaimed. Novel chain transfer agents for use in the process are alsoclaimed.

There is increasing interest in methods for producing a variety ofpolymers with control of the major variables affecting polymerproperties. Living polymerizations provide the maximum degree of controlfor the synthesis of polymers with predictable well defined structures.The characteristics of a living polymerization are discussed by Quirkand Lee (Polymer International 27, 359 (1992)) who give the followingexperimentally observable criteria:

-   -   “1. Polymerization proceeds until all of the monomer has been        consumed. Further addition of monomer results in continued        polymerization.    -   2. The number average molecular weight (or the number average        degree of polymerization) is a linear function of conversion.    -   3. The number of polymer molecules (and active centers) is a        constant which is sensibly independent of conversion.    -   4. The molecular weight can be controlled by the stoichiometry        of the reaction.    -   5. Narrow molecular weight distribution polymers are produced.    -   6. Block copolymers can be prepared by sequential monomer        addition.    -   7. Chain end-functionalized polymers can be prepared in        quantitative yield.”

Living polymerization processes can be used to produce polymers ofnarrow molecular weight distribution containing one or more monomersequences whose length and composition are controlled by thestoichiometry of the reaction and the degree of conversion.Homopolymers, random copolymers or block polymers can be produced with ahigh degree of control and with low polydispersity. Swarc (Adv. Polym.Sci. 49, 1 (1983)) stated that living polymerization to give polymers ofnarrow molecular weight distribution requires the absence of chaintransfer and termination reactions, the elementary reactions being onlyinitiation and propagation, which take place uniformly with respect toall growing polymer chains. Later Inoue and Aida in an article on livingpolymer systems (Encyclopedia of Polymer Science and Engineering,Supplement Volume, Wiley Interscience New York 1989) stated “If chaintransfer and terminating agents are present in the polymerization systemthe living character of the polymerization is lost, and the formation ofpolymer with narrow molecular weight distribution does not result.”

However, it has been shown that if the chain transfer process isreversible then polymerization can still possess most of thecharacteristics of living polymerization. A variety of terms have beenused to describe polymerizations believed to involve this mechanismincluding “immortal polymerization”, equilibration polymerization”,“polymerization with degenerative chain transfer” and “livingpolymerization with reversible chain transfer”. Quirk and Lee (PolymerInternational 27, 359 (1992)), who recommend the last terminology, pointout that the Criteria 3 and 4 mentioned above need to be modified whendescribing these polymerizations to encompass the fact that the totalnumber of polymer molecules is determined by the total number of molesof transfer agent plus the number of moles of initiator.

Block copolymer syntheses by free radical polymerization in the presenceof certain dithiocarbamate or xanthate derivatives as initiator-transferagents-chain terminators (iniferters) have been described. In theseexamples the dithiocarbamate or xanthate derivative is used as aphotochemical initiator. For a discussion of this chemistry see recentreviews [Moad et al. in Comprehensive Polymer Science; Pergamon: London,vol 3, p 141 (1989)]. The dithiocarbamates (for example, benzyldithiocarbanate) have very low transfer constants (<<0.1) and areineffective in the context of the current invention. Greszta et al.(Macromolecules, 27, 638 (1994)) have described the application of chaintransfer chemistry in living radical polymerization and have proposedand rejected the use of dithiocarbamates in this context because of thelow transfer constant and the problem of side reactions. JP 04198303 A2discloses polymerization in the presence of triarylmethyldithiocarboxylates of the following structure

as initiators of polymerization to yield block polymers which may havelow polydispersity (all examples have M_(w)/M_(n) ₃ 1.4). Thesecompounds have a very weak carbon-sulfur bond that cleaves underpolymerization conditions to give a stable triarylmethyl radical and athiocarbonylthiyl radical. The product triarylmethyl radical is known tobe a poor initiator of radical polymerization. They are thus ineffectivein the context of this invention.Rizzardo et al. (Macromol. Symp. 98, 101 (1995)) review polymerizationin the presence of addition-fragmentation chain transfer agents but donot mention the possibility of low polydispersity products.Polymers or oligomers of the following structure are known asmacromonomers.

These macromonomers which are addition-fragmentation chain transferagents are disclosed in J Macromol. Sci.-Chem. A23, 839 (1986) andInternational Patent publications WO 93/22351 and WO 93/22355. Freeradical polymerization with living characteristics utilizing thesemacromonomers as chain transfer agents is disclosed in InternationalPatent Application PCT/US95/14428. The process of this invention has theadvantages of compatibility with a wide range of monomers and reactionconditions and will give good control over molecular weight, molecularweight distribution, i.e., polydispersity, and polymer architecture.

SUMMARY OF THE INVENTION

This invention concerns a process for the synthesis of polymers of thegeneral Formula:

comprising contacting:

-   (i) a monomer (means one or more) selected from the group consisting    of vinyl monomers (of structure CH₂═CUV), maleic anhydride,    N-alkylmaleimide, N-arylmaleimide, dialkyl fumarate and    cyclopolymerizable monomers;-   (ii) a thiocarbonylthio compound selected from:

having a chain transfer constant greater than about 0.1; and

-   (iii) free radicals produced from a free radical source; and-   controlling the polydispersity of the polymer being formed by    varying the ratio of the number of molecules of (ii) to the number    of molecules of (iii);-   the polymer of Formula A being made by contacting (i), (ii)C    and (iii) and the polymer of Formula B being made by contacting    (i), (ii) D and (iii);    wherein:

Z is selected from the group consisting of hydrogen, chlorine,optionally substituted alkyl, optionally substituted aryl, optionallysubstituted heterocyclyl, optionally substituted alkylthio, optionallysubstituted alkoxycarbonyl, optionally substituted aryloxycarbonyl(—COOR″), carboxy (—COOH), optionally substituted acyloxy (—O₂CR″),optionally substituted carbamoyl (—CONR″₂), cyano (—CN), dialkyl- ordiaryl-phosphonato[—P(═O)OR″₂], dialkyl- or diaryl-phosphinato[—P(═O)R″₂], and a polymer chain formed by any mechanism;

Z′ is a m-valent moiety derived from a member of the group consisting ofoptionally substituted alkyl, optionally substituted aryl and a polymerchain; where the connecting moieties are selected from the group thatconsists of aliphatic carbon, aromatic carbon, and sulfur;

Q is selected from the group consisting of

repeating units from maleic anhydride, N-alkylmaleimide,N-arylmaleimide, dialkyl fumarate and cyclopolymerizable monomers;

U is selected from the group consisting of hydrogen, halogen, optionallysubstituted C₁-C₄ alkyl wherein the substituents are independentlyselected from the group that consists of hydroxy, alkoxy, aryloxy (OR″),carboxy, acyloxy, aroyloxy (O₂CR″), alkoxy-carbonyl and aryloxy-carbonyl(CO₂R″);

V is selected from the group consisting of hydrogen, R″, CO₂H, CO₂R″,COR″, CN, CONH₂, CONHR″, CONR″₂, O₂CR″, OR″ and halogen;

R is selected from the group consisting of optionally substituted alkyl;an optionally substituted saturated, unsaturated or aromatic carbocyclicor heterocyclic ring; optionally substituted alkylthio; optionallysubstituted alkoxy; optionally substituted dialkylamino; anorganometallic species; and a polymer chain prepared by anypolymerization mechanism; in compounds C and D, R. is a free-radicalleaving group that initiates free radical polymerization;

R″ is selected from the group consisting of optionally substitutedC₁-C₁₈ alkyl, C₂-C₁₈ alkenyl, aryl, heterocyclyl, aralkyl, alkarylwherein the substituents are independently selected from the group thatconsists of epoxy, hydroxy, alkoxy, acyl, acyloxy, carboxy (and salts),sulfonic acid (and salts), alkoxy- or aryloxy-carbonyl, isocyanato,cyano, silyl, halo, and dialkylamino;

q is 1 or an integer greater than 1;

p is 1 or an integer greater than 1; when p≧2, then R=R′;

m is an integer ≧2; and

R′ is a p-valent moiety derived from a member of the group consisting ofoptionally substituted alkyl, optionally substituted aryl and a polymerchain; where the connecting moieties are selected from the groupconsisting of aliphatic carbon, aromatic carbon, silicon, and sulfur; incompounds C and D, R′. is a free radical leaving group that initiatesfree radical polymerization.

Preferred is a process as described for controlling polydispersity byvarying the ratio of the number of molecules of (ii) to (iii) asfollows:

-   (a) lower polydispersity by increasing the ratio of (ii) to (iii);    and-   (b) increase polydispersity by decreasing the ratio of (ii) to    (iii).    Most preferred is the process in which the ratio of (ii) to (iii) is    increased to obtain a polymer having a polydispersity below about    1.5.

The monomer moieties and value of q in the monomer repeating unit(s)derived from those in (i) are selected so that:

-   when q≧1 and Q is a single monomer species, then the polymer is    homopolymer;-   when q≧2 and Q is selected from 2 or more different monomer species    in irregular sequence then the polymer is copolymer; and-   when q≧2 and Q is selected from 2 or more different monomer species    in which each different monomer or group of monomers appears in a    discrete sequence then the polymer is block copolymer.

The invention also concerns chain transfer agents designated hereafteras (5), (6), (7), (8), (9), (10), (11), (14), (15), (17), (18), (19),(22), (23), (24), (25), (28) and (29). The invention also concernspolymers of Formulae A and B with substituents as defined above. Inpolymers of Formulae A and B, R. and R′. are derived from free radicalleaving group(s) that initiate free radical polymerization, R-(Q)_(q).and R′-(Q)_(q). being the free radical leaving group(s) that initiatefree radical polymerization. Preferred polymers are random, block (mostpreferred), graft, star and gradient copolymers; most especially thosehaving chain-end functionality. Compounds of Formulae C and D can beused to produce branched, homo- or copolymers with the number of armsbeing less than or equal to p in C and m in D.

DEFINITIONS

By polymer chains formed by any mechanism (in Z or R), is meant:condensation polymers such as polyesters (for example, polycaprolactone,polyethylene terephthalate), polycarbonates, poly(alkylene oxide)s [forexample, poly(ethylene oxide), poly(tetramethylene oxide)], nylons,polyurethanes and chain polymers such as poly(meth)acrylates andpolystyrenics.

Cyclopolymerizable monomers are compounds which contain two or moreunsaturated linkages suitably disposed to allow propagation by asequence of intramolecular and intermolecular addition steps leading theincorporation of cyclic units into the polymer backbone. Most compoundsof this class are 1,6-dienes such as—diallylammonium salts (e.g.,diallyldimethylammonium chloride), substituted 1,6-heptadienes (e.g.,6-dicyano-1,6-heptadiene,2,4,4,6-tetrakis(ethoxycarbonyl)-1,6-heptadiene) and monomers of thefollowing generic structure

where substituents K, K′, L, E, E′ are chosen such that the monomerundergoes cyclopolymerization. For example:

E, E′ are independently selected from the group consisting of H, CH₃,CN, CO₂Alkyl, Ph; K, K′ are selected from the group consisting of CH₂,C═O, Si(CH₃)₂, O; L is selected from the group consisting of C(E)₂, O,N(Alkyl)₂ salts, P(Alkyl)₂ salts, P(O)Alkyl. For a further list ofmonomers see Moad and Solomon “The Chemistry of Free RadicalPolymerization”, Pergamon, London, 1995, pp 162-170.

By organometallic species is meant a moiety containing one or more metalatoms from Groups III and IV of the Periodic Table and transitionelements and organic ligands, preferably species such as Si(X)₃, Ge(X)₃and Sn(X)₃ which can be good radical leaving groups and initiatepolymerization.

DETAILS OF THE INVENTION

We have now discovered that free radical polymerizations when carriedout in the presence of certain chain transfer agents of the followingstructure:

have living characteristics and provide polymers of controlled molecularweight and low polydispersity. Chain transfer agents applicable in thisinvention are designated as CTAs hereinafter.

While not wishing to be limited to any particular mechanism, it isbelieved that the mechanism of the process is as summarized in Scheme 1below. Propagating radicals P_(n). are produced by radicalpolymerization. These can react reversibly with the chain transfer agentRA to form an intermediate radical P_(n)A(.)R which fragments to give aradical R. (which adds monomer to reinitiate polymerization) and a newtransfer agent P_(n)A. This new transfer agent P_(n)A has similarcharacteristics to the original transfer agent RA in that it reacts withanother propagating radical P_(m). to form an intermediate radicalP_(n)A(.)P_(m) which fragments to regenerate P_(n). and form a newtransfer agent P_(m)A which has similar characteristics to RA. Thisprocess provides a mechanism for chain equilibration and accounts forthe polymerization having living characteristics.

This invention provides a free radical polymerization process withliving characteristics which process comprises polymerizing one or morefree radically polymerizable monomers in the presence of a source ofinitiating free radicals and a chain transfer agent (CTA) of Formula Cor D which CTA during the polymerization reacts with the initiating orpropagating radicals to give both a new radical that initiates furtherpolymerization and a polymeric CTA also of Formula C or D (where R isthe former initiating or propagating radical) with similarcharacteristics to the original CTA, the reaction conditions beingchosen so that the ratio of the total number of initiator-derivedradicals to the number of CTA molecules is maintained at a minimum valueconsistent with achieving an acceptable rate of polymerization,preferably less than 0.1, and the chain transfer constants of the CTAsare greater than 0.1, preferably greater than 1, and more preferably,greater than 10.

Initiating radicals are free radicals that are derived from theinitiator or other species which add monomer to produce propagatingradicals. Propagating radicals are radical species that have added oneor more monomer units and are capable of adding further monomer units.

All of the benefits which derive from the use of radical polymerizationcan now be realized in syntheses of low polydispersity homo- andcopolymers. The ability to synthesize block, graft, star, gredient andend-functional polymers further extends the value of the process as doescompatibility with protic monomers and solvents.

The source of initiating radicals can be any suitable method ofgenerating free radicals such as the thermally induced homolyticscission of a suitable compound(s) (thermal initiators such asperoxides, peroxyesters, or azo compounds), the spontaneous generationfrom monomer (e.g., styrene), redox initiating systems, photochemicalinitiating systems or high energy radiation such as electron beam, X- orgamma-radiation. The initiating system is chosen such that under thereaction conditions there is no substantial adverse interaction of theinitiator or the initiating radicals with the transfer agent under theconditions of the experiment. The initiator should also have therequisite solubility in the reaction medium or monomer mixture.

Thermal initiators are chosen to have an appropriate half life at thetemperature of polymerization. These initiators can include one or moreof the following compounds:

-   -   2,2′-azobis(isobutyronitrile), 2,2′-azobis(2-cyano-2-butane),        dimethyl 2,2′-azobisdimethylisobutyrate,        4,4′-azobis(4-cyanopentanoic acid),        1,1′-azobis(cyclohexanecarbonitrile),        2-(t-butylazo)-2-cyanopropane,        2,2′-azobis[2-methyl-N-(1,1)-bis(hydroxymethyl)-2-hydroxyethyl]propionamide,        2,2′-azobis[2-methyl-N-hydroxyethyl)]-propionamide,        2,2′-azobis(N,N′-dimethyleneisobutyramidine) dihydrochloride,        2,2′-azobis(2-amidinopropane) dihydrochloride,        2,2′-azobis(N,N′-dimethyleneisobutyramine),        2,2′-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide),        2,2′-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide),        2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],        2,2′-azobis(isobutyramide) dihydrate,        2,2′-azobis(2,2,4-trimethylpentane),        2,2′-azobis(2-methylpropane), t-butyl peroxyacetate, t-butyl        peroxybenzoate, t-butyl peroxyoctoate, t-butyl        peroxyneodecanoate, t-butylperoxy isobutyrate, t-amyl        peroxypivalate, t-butyl peroxypivalate, di-isopropyl        peroxydicarbonate, dicyclohexyl peroxydicarbonate, dicumyl        peroxide, dibenzoyl peroxide, dilauroyl peroxide, potassium        peroxydisulfate, ammonium peroxydisulfate, di-t-butyl        hyponitrite, dicumyl hyponitrite.

Photochemical initiator systems are chosen to have the requisitesolubility in the reaction medium or monomer mixture and have anappropriate quantum yield for radical production under the conditions ofthe polymerization. Examples include benzoin derivatives, benzophenone,acyl phosphine oxides, and photo-redox systems.

Redox initiator systems are chosen to have the requisite solubility inthe reaction medium or monomer mixture and have an appropriate rate ofradical production under the conditions of the polymerization; theseinitiating systems can include combinations of the following oxidantsand reductants:

-   -   oxidants: potassium peroxydisulfate, hydrogen peroxide, t-butyl        hydroperoxide.    -   reductants: iron (II), titanium (III), potassium thiosulfite,        potassium bisulfite.

Other suitable initiating systems are described in recent texts. See,for example, Moad and Solomon “The Chemistry of Free RadicalPolymerization”. Pergamon, London, 1995, pp 53-95.

The process of the invention can be applied to any monomers or monomercombinations which are susceptible to free-radical polymerization. Suchmonomers include those with the general structure:

where U and V are as defined above. Optionally, the monomers areselected from the group that consists of maleic anhydride,N-alkylmaleimide, N-arylmaleimide, dialkyl fumarate andcyclopolymerizable monomers. Monomers CH₂═CUV as used herein includeacrylate and methacrylate esters, acrylic and methacrylic acid, styrene,acrylamide, methacrylamide, and methacrylonitrile, mixtures of thesemonomers, and mixtures of these monomers with other monomers. As oneskilled in the art would recognize, the choice of comonomers isdetermined by their steric and electronic properties. The factors whichdetermine copolymerizability of various monomers are well documented inthe art. For example, see: Greenley, R. Z., in Polymer Handbook 3rdEdition (Brandup, J., and Immergut, E. H Eds.) Wiley: New York, 1989 pII/53.

Specific monomers or comonomers include the following:

methyl methacrylate, ethyl methacrylate, propyl methacrylate (allisomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate,isobornyl methacrylate, methacrylic acid, benzyl methacrylate, phenylmethacrylate, methacrylonitrile, alpha-methylstyrene, methyl acrylate,ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (allisomers), 2-ethylhexyl acrylate, isobornyl acrylate, acrylic acid,benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, functionalmethacrylates, acrylates and styrenes selected from glycidylmethacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate(all isomers), hydroxybutyl methacrylate (all isomers),N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate,triethyleneglycol methacrylate, itaconic anhydride, itaconic acid,glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (allisomers), hydroxybutyl acrylate (all isomers), N,N-dimethylaminoethylacrylate, N,N-diethylaminoethyl acrylate, triethyleneglycol acrylate,methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide,N-tert-butylmethacrylamide, N-n-butylmethacrylamide,N-methylolmethacrylamide, N-ethylolmethacrylamide,N-tert-butylacrylamide, N-n-butylacrylamide, N-methylolacrylamide,N-ethylolacrylamide, vinyl benzoic acid (all isomers),diethylaminostyrene (all isomers), alpha-methylvinyl benzoic acid (allisomers), diethylamino alpha-methylstyrene (all isomers), p-vinylbenzenesulfonic acid, p-vinylbenzene sulfonic sodium salt,trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate,tributoxysilylpropyl methacrylate, dimethoxymethylsilylpropylmethacrylate, diethoxymethyl-silylpropylmethacrylate,dibutoxymethylsilylpropyl methacrylate, diisopropoxymethylsilylpropylmethacrylate, dimethoxysilylpropyl methacrylate, diethoxysilylpropylmethacrylate, dibutoxysilylpropyl methacrylate, diisopropoxysilylpropylmethacrylate, trimethoxysilylpropyl acrylate, triethoxysilylpropylacrylate, tributoxysilylpropyl acrylate, dimethoxymethylsilylpropylacrylate, diethoxymethylsilylpropyl acrylate, dibutoxymethylsilylpropylacrylate, diisopropoxymethylsilylpropyl acrylate, dimethoxysilylpropylacrylate, diethoxysilylpropyl acrylate, dibutoxysilylpropyl acrylate,diisopropoxysilylpropyl acrylate, vinyl acetate, vinyl butyrate, vinylbenzoate, vinyl chloride, vinyl fluoride, vinyl bromide, maleicanhydride, N-phenylmaleimide, N-butylmaleimide, N-vinylpyrrolidone,N-vinylcarbazole, butadiene, isoprene, chloroprene, ethylene, propylene.

Examples of Multifunctional (p≧2) Structures Represented by Formula C

Examples of Multifunctional (m≧2) Structures Represented by Formula D

Many such structures are possible of which the following compounds areillustrative. Additional structures are found in the Examples section.

In the compounds of Formulae C and D substituted rings can have reactivesubstituent groups directly or indirectly attached to the ring by meansof a methylene group or other side chain.

The substituents on groups referred to above for R, R′, R″, Z, Z′ inFormulae A-D and U, V, R″ in the monomer do not take part in thepolymerization reactions but form part of the terminal groups of thepolymer chains and may be capable of subsequent chemical reaction. Thelow polydispersity polymer containing any such reactive group is therebyable to undergo further chemical transformation, such as being joinedwith another polymer chain. Suitable reactive substituents include:epoxy, hydroxy, alkoxy, acyl, acyloxy, carboxy (and salts), sulfonicacid (and salts), alkylcarbonyloxy, isocyanato, cyano, silyl, halo, anddialkylamino. Alternatively, the substituents may be non-reactive suchas alkoxy, alkyl or aryl. Reactive groups should be chosen such thatthere is no adverse reaction with the CTA under the conditions of theexperiment. For example, groups such as primary or secondary amino —NH₂,—NHalkyl) under some conditions may react with dithioesters to givethioamides thus destroying the CTA.

Unless specified otherwise alkyl groups referred to in thisspecification may be branched or unbranched and contain from 1 to 18carbon atoms. Alkenyl groups may be branched or unbranched and containfrom 2 to 18 carbon atoms. Saturated, unsaturated, or aromaticcarbocyclic or heterocyclic rings may contain from 3 to 14 atoms.

“Heterocyclic” or “heterocyclyl” means a ring structure containing 3 to10 atoms at least one of which is selected from O, N and S, which may ormay not be aromatic. Examples of aromatic “heterocyclyl” moieties arepyridyl, furanyl, thienyl, piperidinyl, pyrrolidinyl, pyrazoyl,benzthiazolyl, indolyl, benzofuranyl, benzothiophenyl, pyrazinyl,quinolyl, and the like, optionally substituted with one or more alkyl,haloalkyl, halo, nitro, or cyano groups. “Ph” means phenyl.

An example of the preferred class of CTAs are the dithioesters (FormulaC, p=1) such as are depicted in Scheme 2 which is illustrative of thereaction mechanism believed to be operative in the process of thisinvention. It should be understood, however, that the invention is notlimited to the mechanism depicted and that other mechanisms may beinvolved.

J is a fragment derived from an initiating or propagating radical.

A key feature of the invention is the retention of the activethiocarbonylthio end group [—C(S)—S— ] in the polymeric product. Theinvention thus also provides a route to block polymers as illustrated,for example, in Scheme 3.

J is a fragment derived from an initiating or a propagating radical.

Polymers with complex architectures including multiblock, branched, starand graft polymers are available through the use of reagents containingmultiple thiocarbonylthio groups as indicated by formulae C (where p≧2)and D. The overall process is shown in Scheme 4.

Block, star or graft polymers can be formed from polymers (prepared byany polymerization mechanism) that contain the thiocarbonylthio[—S—C(═S)—] linkage. Methods for forming dithoester and related groupsare well-documented in the art. The following example (Scheme 5) offorming a block copolymer from poly(ethylene oxide) is illustrative ofthe process.

Benefits of the polymerization process described in this invention are:

-   a) Low polydispersity polymers can be synthesized.

In the context of the present invention, low polydispersity polymers arethose with polydispersities that are significantly less than thoseproduced by conventional free radical polymerization. In conventionalfree radical polymerization, polydispersities (the polydispersity isdefined as the ratio of the weight average and number average molecularweights—M_(w)/M_(n)) of the polymers formed are typically in the range1.6-2.0 for low conversions (<10%) and are substantially greater thanthis for higher conversions. Polydispersities obtained with the presentinvention are usually less than 1.5, often less than 1.3 and, withappropriate choice of the chain transfer agent and the reactionconditions, may be less than 1.1. The low polydispersity can bemaintained at high conversions (see Examples).

Note that it is also possible to produce polymers with broad, yetcontrolled, polydispersity or multimodal molecular weight distributionby controlled addition of the CTA over the course of the polymerizationprocess.

Müller et al. have derived relationships which enable polydispersitiesto be estimated for polymerizations which involve chain equilibration byreversible chain transfer (Müller, A. H. E.; Zhuang, R.; Yan, D.;Litvenko, G. Macromolecules, 1995, 28, 4326)M _(w) /M _(n)=1+1/C _(tr)

This above relationship should apply to batch polymerizations carried tofill conversion in the situation where the number of initiator-radicalderived chains is small with respect to total chains and there are noside reactions.

This relationship suggests that the transfer constant should be >2 toobtain a polydispersity <1.5 in a batch polymerization. If the transferconstant is <2, low polydispersities (<1.5) may still be obtained infeed polymerization processes by choosing an appropriate monomer totransfer agent ratio and continuing the polymerization for a sufficientperiod to produce the desired molecular weight and polydispersity. Inthese circumstances, kinetic simulation can be used to aid in selectingreaction conditions.

In theory, it is possible to use reagents with very low transferconstants (<0.1). However, in this case it is likely that side reactionswill complicate the polymerization process. In practice,polydispersities are likely to be higher than predicted by theserelationships because of the limitations already mentioned. Nonetheless,these relationships serve as a useful guide in selecting reactionconditions.

-   b) Molecular weights increase in a predictable and linear manner    with conversion (see Examples) which is controlled by the    stoichiometry. In the case of monofunctional CTAs of Formulae C and    D the molecular weight of the product can be calculated according to    the relationship:

${M\; W_{prod}} = {{\frac{\left\lbrack {{moles}\mspace{14mu}{monomer}\mspace{14mu}{consumed}} \right\rbrack}{\left\lbrack {{moles}\mspace{14mu}{CTA}} \right\rbrack} \times M\; W_{mon}} + {M\; W_{cta}}}$Where:

-   -   MW_(prod) is the number average molecular weight of the isolated        polymer    -   MW_(mon) is the molecular weight of the monomer        -   MW_(cta) is the molecular weight of the CTA of formula C or            D.    -   This expression applies under reaction conditions where the        number of initiator-derived chains is small with respect to        total chains. Note that this form of molecular weight control is        very different to that seen in free radical polymerization in        the presence of conventional transfer agents.

-   c) The process can be used to provide various low polydispersity    polymers including:    -   End-functional polymers    -   Block and multiblock and gradient polymers    -   Star polymers    -   Graft or branched polymers.

-   d) The process of this invention is compatible with a wider range of    monomers and reaction conditions than other processes for producing    low polydispersity and reactive polymers. Specific advantages of the    present process are:    -   i) The much higher transfer constant of compounds of Formula C        or D (transfer constant can be >20) in comparison to        macromonomers (transfer constant <2) means that it is not        necessary to use starved-feed conditions to obtain low        polydispersity polymers or block polymers. It is possible to use        a batch polymerization process (see Examples).    -   ii) The compounds of Formula C or D do not undergo        copolymerization with monomers. Therefore, low polydispersity        polymers based on monosubstituted monomers (e.g., acrylic        monomers, styrene) can be carried out under a wider range of        reaction conditions.

The choice of the CTA compound is important in synthesis of lowpolydispersity polymers. The preferred dithioesters and relatedcompounds give chain transfer with high chain transfer constants.

The transfer constant is defined as the ratio of the rate constant forchain transfer to the rate constant for propagation at zero conversionof monomer and CTA compound. If chain transfer occurs byaddition-fragmentation, the rate constant for chain transfer (k_(tr)) isdefined as follows:

$k_{tr} = {k_{add} \times \frac{k_{\beta}}{k_{- {add}} + k_{\beta}}}$where k_(add) is the rate constant for addition to the CTA and k_(−add)and k_(b) are the rate constants for fragmentation in the reverse andforward directions respectively.

Based on the addition-fragmentation mechanism, four factors can be seento influence the effectiveness of the CTA in the process of thisinvention:

-   a) The rate of reaction of the CTA (RA and AP_(n) in Scheme 1).-   b) The partitioning of the intermediate radicals (P_(n)A.R and    P_(n)A.P_(m) in Scheme 1) between starting materials and products.-   c) The rate of fragmentation of the intermediate radicals (P_(n)A.R    and P_(n)A.P_(m) in Scheme 1).-   d) The ability of the expelled radicals (R. and P_(n). in Scheme 1)    to reinitiate polymerization. Factors a) and b) determine the    magnitude of the transfer constant of the CTA compound.

Preferably, the transfer constant for the addition-fragmentation chaintransfer process is >0.1. The polydispersity obtained under a given setof reaction conditions is sensitive to the value of the transferconstant. Lower polydispersities will result from the use of reagentswith higher transfer constants. Benzyl dithiobenzoate derivatives havetransfer constants which are estimated to be >20 in polymerization ofstyrene or acrylate esters. Higher transfer constants also allow greaterflexibility in the choice of reaction conditions. For reagents with lowchain transfer constants, the use of feed addition is advantageous toobtain low polydispersities.

The chain transfer activity of CTAs of Formula C or D is a function ofthe substituents R and Z and the particular propagating radical. Rshould be chosen so as to be a free radical leaving group under thepolymerization conditions (and yet retain ability to reinitiatepolymerization—see below). In styrene polymerization, dithiobenzoateCTAs (RA in Scheme 1) where A is PhCS₂— and R is —C(Me)₂Ph, —C(Me)₂CN,—C(Me)₂CO₂Alkyl, —C(Me)₂CH₂C(Me)₃, —C(Me)₃, —C(Me)HPh, —CH₂Ph, —CH₂CO₂Hare all effective in giving narrowed polydispersity and molecular weightcontrol under batch polymerization conditions (see Examples). On theother hand, in MMA polymerization, effectiveness decreases in the orderwhere R is: —C(Me)₂Ph³—C(Me)₂CN>—C(Me)₂CO₂Alkyl>—C(Me)₂CH₂C(Me)₃,—C(Me)₃>—C(Me)HPh>—CH₂Ph. Of these reagents, only those dithiobenzoateswhere R=—C(Me)₂Ph or —C(Me)₂CN are effective in giving both narrowedpolydispersity and molecular weight control under batch polymerizationconditions. The dithiobenzoate where R=—C(Me)₂CO₂Et provides goodmolecular weight control but broader polydispersity. These results canbe related to the magnitude of the transfer constant for the CTA and tothe free radical leaving group ability of the R substituent with respectto that of the propagating radical. For example, the dithiobenzoateswith R=—C(Me)HPh and —CH₂Ph, which are ineffective in providing livingcharacteristics to the batch polymerization of MMA at 60° C., havetransfer constants of 0.15 and 0.03 respectively. These R groups arepoor free radical leaving groups with respect to the MMA propagatingradical.

It is also important to bear these considerations in mind in blockcopolymer synthesis. For example, the polystyryl propagating species(—P_(n)=—[CH₂—CHPh]_(n) in Scheme 1) is a poorer free radical leavinggroup than the poly(methyl methacrylate) propagating species(—P_(n)=—[CH₂—C(Me)(CO₂Me)]_(n) in Scheme 1). Thus, for synthesis ofpoly(methyl methacrylate-block-styrene) under batch polymerizationconditions the poly(methyl methacrylate) block is made first in order tomake a narrow polydispersity block copolymer.

If the reaction is carried out under conditions whereby the monomer isfed to maintain a lower monomer to CTA ratio, reagents with lowertransfer constants can be used successfully. Thus, a polystyrenepolymeric CTA has been successfully converted to poly(methylmethacrylate-block-styrene) under feed polymerization conditions.

Z in formulae C and D should be chosen to give a high reactivity of thedouble bond towards addition (while not slowing the rate offragmentation to the extent that there is an unacceptable retardation ofpolymerization—see below). For example, the transfer constant increasesin the series where Z=—NMe₂<—OMe<—SMe<—Me< -Ph. The compound Z=NEt₂,R=CH₂Ph has a very low transfer constant (<0.01) and is ineffective inpolymerizations of styrene and methyl methacrylate and vinyl acetate.Xanthate esters (Z=—O-alkyl) also have low transfer constants inpolymerizations of styrene and methyl methacrylate (0.1) and are noteffective in imparting living characteristics to polymerizations ofthese monomers. These compounds are not part of the present invention.On the other hand, dithiocompounds with Z=—S-alkyl, -alkyl or -aryl (andother substituents as defined herein) have high transfer constants (thecompound Z=Ph, R=CH₂Ph has a transfer constant of >20 in styrenepolymerization at 60° C.) and are effective.

Factors c) and d), as set out above, determine whether or not there isretardation of polymerization and the extent of any retardation. If theoverall rate of reinitiation is greater than or equal to the rate ofpropagation there will be no retardation. These factors will beinfluenced by the substituents R and Z in formulae C and D and thenature of the propagating radical.

We have also found that the relative rates of addition and offragmentation can be estimated using molecular orbital calculations (Fordetails of the method see Moad, G., Moad, C. L., Rizzardo, E., andThang, S. H., Macromolecules, 1996, 29, 7717). This method andinformation on radical reactivities (see for example Moad and Solomon“The Chemistry of Free Radical Polymerization”, Pergamon. London, 1995),when taken together with the information provided herein, will assistthose skilled in the art in selecting transfer agents for particularpolymerizations.

For heterogeneous polymerization, it is desirable to choose a CTA whichhas appropriate solubility parameters. For aqueous emulsionpolymerization, the CTA should preferably partition in favour of theorganic (monomer) phase and yet have sufficient aqueous solubility thatit is able to distribute between the monomer droplet phase and thepolymerization locus.

The choice of polymerization conditions is also important. The reactiontemperature will influence the rate parameters discussed above. Forexample, higher reaction temperatures will typically increase the rateof fragmentation. Conditions should be chosen such that the number ofchains formed from initiator-derived radicals is minimized to an extentconsistent with obtaining an acceptable rate of polymerization.Termination of polymerization by radical-radical reaction will lead tochains which contain no active group and therefore cannot bereactivated. The rate of radical-radical termination is proportional tothe square of the radical concentration. Furthermore, in the synthesisof block star or branched polymers, chains formed from initiator-derivedradicals will constitute a linear homopolymer impurity in the finalproduct. These reaction conditions therefore require careful choice ofthe initiator concentration and, where appropriate, the rate of theinitiator feed.

It is also desirable to choose other components of the polymerizationmedium (for example, the solvents, surfactants, additives, andinitiator) such that they have a low transfer constant towards thepropagating radical. Chain transfer to these species will lead to theformation of chains which do not contain the active group.

As a general guide in choosing conditions for the synthesis of narrowpolydispersity polymers, the concentration of initiator(s) and otherreaction conditions (solvent(s) if any, reaction temperature, reactionpressure, surfactants if any, other additives) should be chosen suchthat the molecular weight of polymer formed in the absence of the CTA isat least twice that formed in its presence. In polymerizations wheretermination is solely by disproportionation, this equates to choosing aninitiator concentration such that the total moles of initiating radicalsformed during the polymerization is less than 0.5 times that of thetotal moles of CTA. More preferably, conditions should be chosen suchthat the molecular weight of polymer formed in the absence of the CTA isat least 5-fold that formed in its presence ([initiatingradicals]/[CTA]<0.2).

Thus, the polydispersity can be controlled by varying the number ofmoles of CTA to the number of moles initiating radicals. Lowerpolydispersities are obtained by increasing this ratio; higherpolydispersities are obtained by decreasing this ratio.

With these provisos, the polymerization process according to the presentinvention is performed under the conditions typical of conventionalfree-radical polymerization. Polymerization employing the abovedescribed CTAs is suitably carried out with temperatures during thereaction in the range −20 to 200° C., preferably in the range 40-160° C.

The process of this invention can be carried out in emulsion, solutionor suspension in either a batch, semi-batch, continuous, or feed mode.Otherwise-conventional procedures can be used to produce narrowpolydispersity polymers. For lowest polydispersity polymers, the CTA isadded before polymerization is commenced. For example, when carried outin batch mode in solution, the reactor is typically charged with CTA andmonomer or medium plus monomer. To the mixture is then added the desiredamount of initiator and the mixture is heated for a time which isdictated by the desired conversion and molecular weight. Polymers withbroad, yet controlled, polydispersity or with multimodal molecularweight distribution can be produced by controlled addition of the CTAover the course of the polymerization process.

In the case of emulsion or suspension polymerization the medium willoften be predominantly water and the conventional stabilizers,dispersants and other additives can be present. For solutionpolymerization, the reaction medium can be chosen from a wide range ofmedia to suit the monomer(s) being used.

As has already been stated, the use of feed polymerization conditionsallows the use of CTAs with lower transfer constants and allows thesynthesis of block polymers that are not readily achieved using batchpolymerization processes. If the polymerization is carried out as a feedsystem the reaction can be carried out as follows. The reactor ischarged with the chosen medium, the CTA and optionally a portion of themonomer(s). Into a separate vessel is placed the remaining monomer(s).Initiator is dissolved or suspended in reaction medium in anotherseparate vessel. The medium in the reactor is heated and stirred whilethe monomer+medium and initiator+medium are introduced, for example by asyringe pump or other pumping device. The rate and duration of feed isdetermined largely by the quantity of solution, the desiredmonomer/CTA/initiator ratio and the rate of the polymerization. When thefeed is complete, heating can be continued for an additional period.

Following completion of the polymerization, the polymer can be isolatedby stripping off the medium and unreacted monomer(s) or by precipitationwith a non-solvent. Alternatively, the polymer solution/emulsion can beused as such, if appropriate to its application.

The invention has wide applicability in the field of free radicalpolymerization and can be used to produce polymers and compositions forcoatings, including clear coats and base coat finishes or paints forautomobiles and other vehicles or maintenance finishes for a widevariety of substrates. Such coatings can further include pigments,durability agents, corrosion and oxidation inhibitors, rheology controlagents, metallic flakes and other additives. Block and star, andbranched polymers can be used as compatibilisers, thermoplasticelastomers, dispersing agents or rheology control agents. Additionalapplications for polymers of the invention are in the fields of imaging,electronics (e.g., photoresists), engineering plastics, adhesives,sealants, and polymers in general.

Preferred chain transfer agents applicable in the process of thisinvention are as follows:

EXAMPLES 1 TO 18 Preparation of Thiocarbonylthio Compounds

The processes for making compounds (3) to (29) are as follows:Procedures 1-11 describe the preparation of known CTA compounds.Examples 1-18 describe the synthesis of novel CTA compounds.

Procedure 1 Preparation of Dithiobenzoic acid and 4-chlorodithiobenzoicacid

Dithiobenzoic acid and 4-chlorodithiobenzoic acid were preparedaccording to known procedures. For instance, see the method described inGerman Patent 1,274,121 (1968); (CA70: 3573v).

Procedure 2 Preparation of benzyl dithiobenzoate (3) (C, p=1, R=CH₂Ph,Z=Ph)

This title compound was prepared by a modification of the one-potprocedure described in Recueil, 92, 601 (1973). Phenyl magnesium bromidewas prepared from bromobenzene (62.8 g) and magnesium turnings (10 g) indry tetrahydrofuran (300 mL). The solution was warmed to 40° C. andcarbon disulfide (30.44 g) was added over 15 minutes whilst maintainingthe reaction temperature at 40° C. To the resultant dark brown mixturewas added benzyl bromide (76.95 g) over 15 minutes. The reactiontemperature was raised to 50° C. and maintained at that temperature fora further 45 minutes. Ice water (1.5 L) was added and the organicproducts extracted with diethyl ether (total 2 L). The ethereal phasewas washed with water (1 L), brine (500 mL) and dried over anhydrousmagnesium sulfate. After removal of solvent and vacuum distillation ofthe residue, benzyl dithiobenzoate (3) was obtained as a red oil (60.2g, 61.7% yield), b.p. 152° C. (0.02 mmHg) [lit (Beilstein, E III 9,1998): b.p. 179-180° C. at 3 mmHg]. ¹H-nmr (CDCl₃) d (ppm): 4.60 (s,2H); 7.30-7.60 (m, 5H) and 8.02 (m, 2H).

Procedure 3 Preparation of 1-phenylethyl dithiobenzoate (4) (C, p=1,R=CH(CH₃)Ph, Z=Ph)

Dithiobenzoic acid (9.9 g), styrene (10 mL) and carbon tetrachloride (30mL) were combined and the mixture heated at 70° C. for 4 hours. Theresultant mixture was reduced to a crude oil. The yield of 1-phenylethyldithiobenzoate (4) was 43.4% after purification by column chromatography(aluminium oxide (activity III), petroleum spirit 40-60° C. eluent).¹H-nmr (CDCl₃) d (ppm): 1.92 (d, 3H); 5.39 (q, 1H); 7.34-7.62 (m, 8H)and 8.08 (m, 2H).

Example 1 Preparation of 2-phenylprop-2-yl dithiobenzoate (5) (C, p=1,R=C(CH₃)₂Ph, Z=Ph)

A mixture of dithiobenzoic acid (10.59 g), a-methylstyrene (10 g) andcarbon tetrachloride (40 mL) was heated at 70° C. for 4 hours. Theresultant mixture was reduced to a crude oil which was purified bycolumn chromatography (aluminium oxide (activity III), n-hexane eluent)to give 2-phenylprop-2-yl dithiobenzoate (5) (6.1 g, 32.6% yield) as adark purple oil. ¹H-nmr (CDCl₃) d (ppm): 2.03 (s, 6H); 7.20-7.60 (m, 8H)and 7.86 (m, 2H).

Example 2 Preparation of 1-acetoxyethyl dithiobenzoate (6) (C, p=1,R=CH(CH₃)OAc; Z=Ph)

A mixture of dithiobenzoic acid (4 g), vinyl acetate (10 mL) and carbontetrachloride (15 mL) was heated at 70° C. for 16 hours. The resultantmixture was reduced and the residue purified by column chromatography(aluminium oxide column (activity III), n-hexane eluent) to give1-acetoxyethyl dithiobenzoate (6) (3.21 g, 51.5% yield) as a dark redoil. ¹H-nmr (CDCl₃) d (ppm): 1.80 (d, 3H); 2.09 (s, 3H); 6.75 (q, 1H);7.34-7.60 (m, 3H) and 7.97 (m, 2H).

Example 3 Preparation of hexakis(thiobenzoylthiomethyl)benzene (9, Z=Ph)(C, p=6, R=C₆(CH₂)₆, Z=Ph)

Hexakis(thiobenzoylthiomethyl)benzene was prepared fromhexakis(bromomethyl)benzene according to the method described for thepreparation of benzyl dithiobenzoate (3) with the modification that thereaction mixture was heated at 50° C. for 3 hours. After the usualwork-up, recrystallization from chloroform/ethanol gave the titlecompound as a red solid (77% yield), m.p. 222-224° C. (dec). ¹H-nmr(CDCl₃) d (ppm): 4.66 (s, 12H); 7.30-7.60 (m, 18H) and 7.94 (m, 12H).

Example 4 Preparation of 1,4-bis(thiobenzoylthiomethyl)benzene (8, Z=Ph)(C, p=2, R=C₆H₄(CH₂)₂, Z=Ph)

1,4-Bis(thiobenzoylthiomethyl)benzene was prepared froma,a′-dibromo-p-xylene according to the method described for thepreparation of benzyl dithiobenzoate (3) with the modification that thereaction mixture was heated at 40° C. for 1.5 hours. After the usualwork-up, recrystallization from ethanol gave the title compound as a redsolid (66.7% yield), m.p. 95-97° C. ¹H-nmr (CDCl₃) d (ppm): 4.60 (s,4H); 7.34-7.60 (m, 6H) and 8.00 (m, 4H).

Example 5 Preparation of 1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene(9) (C, p=4, R=C₆H₂(CH₂)₄, Z=Ph)

1,2,4,5-Tetrakis(thiobenzoylthiomethyl)benzene was prepared from1,2,4,5-tetrakis-(bromomethyl)benzene according to the method describedfor the preparation of benzyl dithiobenzoate (3) with the modificationthat the reaction mixture was heated at 40° C. for 1 hour. The usualwork-up gave a red solid which was recrystallized from 1:4benzene/ethanol to give 1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene(47% yield), m.p. 142-143.5° C. (dec). ¹H-nmr (CDCl₃) d (ppm): 4.65 (s,8H); 7.30-7.58 (m, 14H) and 7.97 (m, 8H).

Example 6 Preparation of 1,4-bis-(2-(thiobenzoylthio)prop-2-yl)benzene(10) (C, p=2, R=1,4-C₆H₄(C(CH₃)₂)₂, Z=Ph)

1,4-diisopropenylbenzene (3.96 g) was added to a solution ofdithiobenzoic acid (8 g) in carbon tetrachloride (50 mL) and the mixtureheated at 70° C. for 16 hours. Removal of the solvent, followed bytrituration with 1:2 diethyl ether/n-hexane allowed isolation of thetitle compound as a purple solid (2.87 g, 24.6% yield), m.p. 143-145° C.(dec). ¹H-nmr (CDCl₃) d (ppm): 2.00 (s, 12H); 7.33 (m, 4H); 7.49 (m,2H); 7.50 (s, 4H) and 7.86 (m, 4H).

Example 7 Preparation of 1-(4-methoxyphenyl)ethyl dithiobenzoate (11)(C, p=1, R=4-CH₃OC₆H₄(CH₃)CH; Z=Ph)

A mixture of dithiobenzoic acid (3.6 g), 4-vinylanisole (2.9 g) andcarbon tetrachloride (20 mL) were heated at 70° C. overnight. Thesolvent was evaporated and the residue subjected to columnchromatography (aluminium oxide (activity 111) column, 2% diethyl etherin n-hexane eluent) which gave the title compound (53% yield). ¹H-nmr(CDCl₃) d (ppm): 1.80 (d, 3H, SCHCH₃); 3.80 (s, 3H, OCH₃); 5.22 (q, 1H,SCHCH₃) and 6.88-7.97 (m, 9H, ArH).

Procedure 4 Preparation of benzyl dithioacetate (12) (C, p=1, R=CH₂Ph;Z=CH₃)

Methyl magnesium chloride (10 mL, 3M solution in THF) was diluted withTHF (10 mL) and the resulting solution warmed to 40° C. Carbon disulfide(2.28 g, 0.03 mol) was added over 10 minutes while maintaining thereaction temperature at 40° C. The reaction was cooled to roomtemperature before adding benzyl bromide (5.1 g, 0.03 mol) over 15minutes. The reaction temperature was increased to 50° C. and maintainedfor a further 45 minutes. Water (100 mL) was added and the organicproducts extracted with n-hexane (3×60 mL). The combined organicextracts were washed with water, brine and dried over anhydrousmagnesium sulfate. After removal of solvent and column chromatography(Kieselgel-60, 70-230 mesh, 5% diethyl ether in n-hexane eluent), purebenzyl dithioacetate was obtained as a golden oil (3 g, 55% yield).¹H-nmr (CDCl₃) d (ppm): 2.90 (s, 3H); 4.46 (s, 2H) and 7.31 (m, 5H).

Procedure 5 Preparation of ethoxycarbonylmethyl dithioacetate (13) (C,p=1, R=CH₂COOEt; Z=CH₃)

Methyl magnesium chloride (10 mL, 3M solution in THF) was diluted withTHF (10 mL) and the resulting solution warmed to 40° C. Carbon disulfide(2.28 g, 0.03 mol) was added over 10 minutes while maintaining thereaction temperature at 40° C. The reaction was cooled to roomtemperature before adding ethyl bromoacetate (5.01 g, 0.03 mol) over 15minutes. The reaction temperature was increased to 50° C. and maintainedfor a further 4 hours. Water (100 mL) was added and the organic productswere extracted with ethyl acetate (3×60 mL). The combined organicextracts were washed with water, brine and dried over anhydrousmagnesium sulfate. After removal of solvent and column chromatography(Kieselgel-60, 70-230 mesh, 10% diethyl ether in n-hexane eluent), pureethoxycarbonylmethyl dithioacetate was obtained as a golden oil (1.3 g,24.3% yield). ¹H-nmr (CDCl₃) d (ppm): 1.25 (t, 3H); 2.90 (s, 3H); 4.07(s, 2H) and 4.20 (q, 2H).

Example 8 Preparation of 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate (14)(C, p=1, R=C(CH₃)₂COOEt; Z Ph)

Phenyl magnesium bromide was prepared from bromobenzene (6.28 g, 0.04mol) and magnesium turnings (1 g) in dry THF (30 mL). The solution waswarmed to 40° C. and carbon disulfide (3.05 g, 0.04 mol) was added over15 minutes while maintaining the reaction temperature at 40° C. To theresultant dark brown solution was added ethyl a-bromoisobutyrate (7 g,0.036 mol). The reaction temperature was raised to 80° C. and maintainedfor 60 hours. Ice water (50 mL) was added and the organic products wereextracted with diethyl ether (3×50 mL). The combined organic extractswere washed with water, brine and dried over anhydrous magnesiumsulfate. After removal of solvent and purification by columnchromatography (Kieselgel-60, 70-230 mesh, n-hexane/diethyl ether (9:1)eluent), 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate was obtained as ared oil (4.52 g, 42.2% yield). ¹H-nmr (CDCl₃) d (ppm): 1.25 (t, 3H,CH₂CH₃), 1.77 (s, 6H, 2×CH₃), 4.17 (q, 2H, OCH₂CH₃), 7.35 (dd, 2H,meta-ArH), 7.52 (dd, 1H, para-ArH) and 7.95 (d, 2H, ortho-ArH).

Example 9 Preparation of 2-cyanoprop-2-yl dithiobenzoate (15) (C, p=1,R=C(CH₃)₂CN; Z=Ph)

2-Bromo-2-cyanopropane was prepared by the procedure of Chrzaszczewskaand Popiel (Roczniki Chem., 7, 74-8 (1927); Chem. Abstr., (1928)22:1343⁶). 2-Cyanoprop-2-yl dithiobenzoate (15) was prepared from2-bromo-2-cyanopropane by a method similar to that used to preparecompound (14) with the modification that the reaction was maintained at50° C. for 24 hours. After work-up and purification (columnchromatography on Kieselgel-60, 70-230 mesh, n-hexane/diethyl ether 9:1eluent), 2-cyanoprop-2-yl dithiobenzoate (15) was obtained as a dark redoil (1.9 g, 43% yield). ¹H-nmr (CDCl₃) d (ppm): 1.95 (s, 6H, 2×CH₃),7.38 (dd, 2H, meta-ArH), 7.57 (dd, 1H, para-ArH) and 7.92 (d, 2H,ortho-ArH). ¹³C-nmr (CDCl₃) d (ppm): 26.5, 41.7, 120.0 (CN), 126.6,128.5, 132.9, 144.5 and 227.

Procedure 6 Preparation of tert-butyl dithiobenzoate (16) (C, p=1,R=C(CH₃)₃; Z=Ph)

The synthesis of t-butyl dithiobenzoate (16) was carried out in twosteps.

-   i) S-t-butyl thiobenzoate 1-Butyl mercaptan (6.15 g, 0.068 mol) was    added dropwise to a solution of benzoyl chloride (10.5 g, 0.075 mol)    in pyridine (6 g). The resulting mixture was allowed to stir for two    hours at room temperature then poured onto ice-water and the mixture    extracted with diethyl ether. The organic extract was washed with    dilute HCl, water and brine and finally dried over anhydrous sodium    sulfate. After removal of solvent and vacuum distillation, S-t-butyl    thiobenzoate was obtained (6.64 g, 50.1% yield), b.p. 86° C. (0.8    mmHg). ¹H-nmr (CDCl₃) d (ppm): 1.60 (s, 9H, 3×CH₃), 7.41 (m, 2H,    ArH), 7.54 (m, 1H, ArH) and 7.94 (d, 2H, ArH). ¹³C-nmr (CDCl₃) d    (ppm): 29.8, 48.0, 126.8, 128.3, 132.7, 138.6 and 192.9.-   ii) t-Butyl Dithiobenzoate

A mixture of S-t-butyl thiobenzoate (1.94 g, 0.01 mol) and Lawesson'sreagent (2.43 g, 0.006 mol) in anhydrous toluene (10 mL) was refluxedfor 25 hours. After cooling to room temperature, the reaction mixturewas concentrated and the residue subjected to column chromatography(Kieselgel-60, 70-230 mesh, petroleum spirit/diethyl ether 19:1) Thetitle compound was obtained as an oil, 1.37 g (65.5%). ¹H-nmr (CDCl₃) d(ppm): 1.69 (s, 9H, 3×CH₃), 7.36 (m, 2H, meta-ArH), 7.50 (m, 1H,para-ArH) and 7.88 (d, 2H, ortho-ArH).

¹³C-nmr (CDCl₃) d (ppm): 28.2, 52.2, 126.6, 128.1, 131.7 and 147.0. Thesignal due to C=S (d>220.0 ppm) was beyond the frequency range of thespectrum.

Example 10 Preparation of 2,4,4-trimethylpent-2-yl dithiobenzoate (17)(C, p=1, R=C(CH₃)₂CH₂C(CH₃)₃; Z=Ph)

A mixture of dithiobenzoic acid (5 g), 2,4,4-trimethylpentene (7.3 g)and carbon tetrachloride (25 mL) was heated at 70° C. for two days. Theresultant mixture was reduced to a crude oil. Purification of theresidue, by column chromatography (Kieselgel-60, 70-230 mesh, petroleumspirit 40-60° C. eluent) gave 2,4,4-trimethylpent-2-yl dithiobenzoate(17) (2.74 g, 31.7% yield) as a dark red oil. ¹H-nmr (CDCl₃) d (ppm):1.08 (s, 9H, 3×CH₃), 1.77 (s, 6H, 2×CH₃), 2.20 (s, 2H, CH₂), 7.35 (dd,2H, meta-ArH), 7.49 (dd, 1H, para-ArH) and 7.85 (d, 2H, ortho-ArH).¹³C-nmr (CDCl₃) d (ppm): 28.3, 31.5, 32.8, 50.5, 57.7, 126.6, 128.1,131.5 and 147.9. The signal due to C=S (d>220.0 ppm) was beyond thefrequency range of the spectrum.

Example 11 Preparation of 2-(4-chlorophenyl)prop-2-yl dithiobenzoate(18) (C, p=1, R=4-ClC₆H₄(CH₃)₂C; Z=Ph)

Dithiobenzoic acid (6.3 g) and 4-chloro-a-methylstyrene (6 g) werecombined and the mixture heated at 70° C. overnight. The residue wassubjected to column chromatography (Kieselgel-60, 70-230 mesh, n-hexaneas eluent) which gave the title compound as a purple solid (34.2% yield)m.p. 77-78° C. ¹H-nmr (CDCl₃) d (ppm): 1.97 (s, 6H, 2×CH₃), 7.20-7.52(m, 7H, ArH) and 7.86 (d, 2H. ArH). ¹³C-nmr (CDCl₃) d (ppm): 28.4, 55.7,126.5, 128.1, 131.9, 132.4, 142.8. 146.0. The signal due to C=S (d>220.0ppm) was beyond the frequency range of the spectrum.

Example 12 Preparation of 3- & 4-vinylbenzyl dithiobenzoates (19) (C,p=1, R CH₂CHC₆H₄CH₂; Z=Ph)

A mixture of 3- & 4-vinylbenzyl dithiobenzoate (19) was synthesized froma mixture of 3- & 4-(chloromethyl)styrene by a procedure similar to thatused for compound (14). The reaction was maintained at 50° C. for 24hours. After work-up and column chromatography (aluminium oxide(activity II-III), n-hexane/diethyl ether 49:1 eluent) the mixture of 3-& 4-vinylbenzyl dithiobenzoate (19) was obtained in 42% yield as a redoil. ¹H-nmr (CDCl₃) d (ppm): 4.60 (s, 2H, CH₂), 5.28 (d, 1H, CH₂═CH),5.77 (d, 1H, CH₂═CH), 6.72 (dd, 1H, CH₂═CH), 7.20-7.60 (m, 7H, ArH) and8.00 (d, 2H, ArH).

Procedure 7 Preparation of S-benzyl diethoxypbosphinyldithioformate (20)(C, p=1, R=CH₂Ph; Z=(EtO)₂P(O))

The title compound (20) was prepared by adapting the procedure describedby Grisley, J. Org. Chem., 26, 2544 (1961).

To a stirred slurry of sodium hydride (60% dispersion in mineral oil) (8g, 0.2 mol) in tetrahydrofuran (200 mL) was added diethyl phosphite(27.5 g, 0.2 mol) dropwise under nitrogen. The mixture was stirred untilhydrogen evolution ceased (about 15 minutes). The mixture was allowed tocool in an ice-water bath and carbon disulfide (76 g, 1 mol) was addedover 15 minutes followed by benzyl chloride (25.2 g, 0.2 mol) in THF(100 mL) over 20 minutes. The resultant mixture was stirred at roomtemperature for 24 hours. Diethyl ether (200 mL) was added and themixture washed with water (3×200 mL). The organic layer was dried(MgSO₄), filtered and evaporated in vacuo. After column chromatography(Kieselgel-60, 70-230 mesh, 1:4 ethyl acetate/n-hexane eluent), benzyldiethoxyphosphinyldithioformate (20) was obtained (11 g, 18% yield) as ared oil ¹H-nmr (CDCl₃) d (ppm) 1.43 (t, 6H); 4.38 (s, 2H), 4.65 (q, 4H)and 7.30-7.45 (m, 5H).

Procedure 8 Preparation of tert-butyl trithioperbenzoate (21) (C, p=1;R=(CH₃)₃CS; Z=Ph)

The title compound (21) was prepared according to the proceduredescribed by Aycock and Jurch, J. Org. Chem., 44, 569-572, (1979). Theresidue was subjected to column chromatography (Kieselgel-60, 70-230mesh, n-hexane eluent) to give the product, tert-butyltrithioperbenzoate (21) as a dark purple oil in 60% yield. ¹H-nmr(CDCl₃) d (ppm) 1.32 (s, 9H), 7.45 (m, 3H) and 8.00 (m, 2H).

Example 13 Preparation of 2-phenylprop-2-yl 4-chlorodithiobenzoate (22)(C, p=1, R=C(CH₃)₂Ph; Z=p-ClC₆H₄)

A mixture of 4-chlorodithiobenzoic acid (13 g) and a-methylstyrene (15mL) were heated at 70° C. for 1 hour. To the reaction mixture was addedn-hexane (30 mL) and heating was continued at 70° C. for 16 hours. Theresultant mixture was reduced to a crude oil. Purification, of the oilby chromatography (aluminium oxide column (activity II-III) n-hexaneeluent) gave the title compound (22) as a purple oil (8.5 g, 40%).¹H-nmr (CDCl₃) d (ppm) 2.00 (s, 6H); 7.30 (m, 5H); 7.55 (d, 2H) and 7.83(d, 2H).

Example 14 Preparation of 2-phenylprop-2-yl 1-dithionaphthalate (23) (C,p=1, R=C(CH₃)₂Ph; Z=1-naphthyl)

The procedure was analogous to that used for the preparation of compound(5). The reaction of 1-(chloromethyl)naphthalene (17.6 g, 0.1 mol),sulfur (6.4 g, 0.2 mol) and sodium methoxide (25% solution in methanol,46 mL) in methanol (50 mL) gave 1-dithionaphthoic acid (10 g, 49%). Amixture of 1-dithionaphthoic acid (10 g) and a-methylstyrene (10 mL) incarbon tetrachloride (20 mL) was heated at 70° C. for 16 hours. Afterremoval of carbon tetrachloride and unreacted a-methylstyrene, theresidue was chromatographed (Kieselgel-60, 70-230 mesh, 5% diethyl etherin n-hexane eluent) to yield 2-phenylprop-2-yl 1-dithionaphthalate (23)(9.2 g, 58%) as a dark red oil. ¹H-nmr (CDCl₃) d (ppm) 2.06 (s, 6H);7.29-7.55 (m, 7H); 7.66 (m, 2H); 7.85 (m, 2H) and 8.00 (m, 11H).

Example 15 Preparation of 4-cyanopentanoic acid dithiobenzoate (24) (C,p=1, R=C(CH₃)(CN)(CH₂)₃CO₂H; Z=Ph)

Compound (24) can be made by a procedure analogous to that used forpreparation of compounds (14) and (15). m.p. 97-99° C. ¹H-nmr (CDCl₃) 6rpm) 1.95 (s, 3H); 2.40-2.80 (m, 4H); 7.42 (m, 2H); 7.60 (m, 1H) and7.91 (m, 2H).

Example 16 Preparation of dibenzyl tetrathioterephthalate (25) (D, m=2,R=CH₂Ph; Z′=1,4-phenylene)

The sodium salt of tetrathioterephthalic acid was obtained from thereaction of a,a′-dibromo-p-xylene (6.6 g, 25 mmol), elemental sulfur(3.2 g, 0.1 mol), and sodium methoxide (25% in methanol, 24 mL, 0.1 mol)in methanol (30 mL) at 70° C. for 5 hours. The reaction mixture wasevaporated to dryness and then dissolved in acetonitrile (50 mL). Thiswas treated with benzyl chloride (6.3 g, 50 mmol) at room temperaturefor 16 hours. The suspension was filtered, the solid collected andextracted with chloroform/water. The organic extract was dried andreduced to give the title compound as a red solid (2.14 g, 21%). Meltingpoint: 111-116° C. (dec.). ¹H-nmr (CDCl₃) d (ppm) 4.60 (s, 4H),7.30-7.45 (m, 10H) and 7.97 (s, 4H).

Procedure 10 Preparation of dibenzyl trithiocarbonate (26) (C, p=1,R=CH₂Ph; Z=SCH₂Ph)

The title compound was prepared according to the procedure described byLeung, M-K., et al, J. Chem. Research (S), 478-479, (1995).

Procedure 11 Preparation of carboxymethyl dithiobenzoate (27) (C, p=1,R=CH₂COOH; Z=Ph)

The title compound was prepared according to the procedure of Jensen andPedersen, Acta Chem. Scand., 15, 1087-1096 (1961). ¹H-nmr (CDCl₃) d(ppm) 4.24 (s, 2H), 7.43-8.00 (m, 5H) and 8.33 (s, 1H).

Example 17 Preparation of poly(ethylene oxide) with dithiobenzoate endgroup (28) (C, p=1, R=CH₂COO—(CH₂CH₂O)_(n)Me; Z=Ph)

A mixture of carboxymethyl dithiobenzoate (27) (0.5 g, 2.36 mmol),polyethylene glycol monomethyl ether (MWt. 750) (1.7 g, 2.36 mmol),anhydrous pyridine (2 mL), dicyclohexylcarbodiimide (1.46 g, 7.1 mmol)and 4-toluenesulfonic acid (10 mg) was stirred under nitrogen at 50° C.for 16 hours. The mixture was reduced in vacuo and the residuepartitioned between chloroform (10 mL) and saturated aqueous sodiumbicarbonate (2 mL). The organic phase was dried over anhydrous sodiumsulfate and reduced to a red oil (quantitative yield based on 24).¹H-nmr (CDCl₃) d (ppm) 3.35 (s, 3H), 3.53 (br.t, 2H), 3.65 (s, 50H), 3.7(br.t, 2H), 4.23 (s, 2H), 4.30 (br.t, 2H), 7.38 (t, 2H), 7.54 (t, 1H),8.0 (d, 2H).

Example 18 Preparation of poly(ethylene oxide) with dithiobenzoate endgroup (29) (C, p=1, R=C(CH₃)(CN)CH₁₂CH₂COO—(CH₂CH₂O)_(n)Me; Z=Ph)

A mixture of 4-cyano-4-(thiobenzoylthio)pentanoic acid (24) (0.23 g),polyethylene glycol monomethyl ether (1.8 g, MWt 750) and a catalyticamount of 4-(N,N-dimethylamino)pyridine in dichloromethane (5 mL) wasadded by a solution of dicyclohexylcarbodiimide (0.34 g) indichloromethane (5 mL) at room temperature under nitrogen. The mixturewas stirred for two hours and filtered to remove the dicyclohexylureaby-product. The fitrate was extracted with water seven times (7×10 mL),dried over anhydrous magnesium sulfate and reduced to a red waxy solid(quantitative yield based on 24). ¹H-nmr (CDCl₃) d (ppm) 1.92 (s, 3H),2.60-2.72 (m, 4H), 3.35 (s, 3H), 3.53 (m, 2H), 3.63 (s, 64H), 3.65 (m,2H), 4.26 (t, 2H), 7.40 (t, 2H), 7.57 (t, 1H) and 7.91 (d, 2H).

The following Examples 19-88 represent non-limiting examples whichdemonstrate the operation of the process and the products obtainablethereby.

EXAMPLES 19 TO 88 General Experimental Conditions

In all instances, monomers were purified (to remove inhibitors) andflash-distilled immediately prior to use. The experiments referred to ascontrols were experiments run without the CTA unless otherwisespecified. For polymerizations performed in ampoules, degassing wasaccomplished by repeated freeze-evacuate-thaw cycles. Once degassing wascomplete, the ampoules were flame sealed under vacuum and completelysubmerged in an oil bath at the specified temperature for the specifiedtimes. The percentage conversions were calculated gravimetrically unlessotherwise indicated.

The structures of polymers and block copolymers have been verified byapplication of appropriate chromatographic and spectroscopic methods.Gel permeation chromatography (GPC) has been used to establish themolecular weight and molecular weight distribution (polydispersity) ofthe polymers. Unless otherwise specified, a Waters Associates liquidchromatograph equipped with differential refractometer and 10⁶, 10⁵,10⁴, 10³, 500 and 100 Å Ultrastyragel columns was used. Tetrahydrofuran(flow rate of 1.0 mL/min) was used as eluent. The molecular weights areprovided as polystyrene equivalents. The terms M_(n), M_(w) andM_(w)/M_(n) are used to indicate the number and weight average molecularweights and the polydispersity respectively. Theoretical molecularweights [M_(n) (calc)] were calculated according to the followingexpression:M _(n)(calc)=[monomer]/[CTA]×conversion×MWt of monomerFor low molecular weight polymers (degree of polymerization <50), theend group [ZC(═S)S—] can be determined by ¹H NMR spectroscopy. In caseswhere the end group is (Aryl)C(═S)S— or (Alkyl)C(═S)S— the end groupscan be observed in polymers with degree of polymerization ²1000 byUV-Visible spectrophotometry. Gel permeation chromatography coupled withUV-Visible spectrophotometry enables a measurement of the purity ofblock copolymers in these cases.

Example 19 Preparation of low polydispersity poly(methyl methacrylate)using 2-phenylprop-2-yl dithiobenzoate (5)

A stock solution containing methyl methacrylate (15 mL),azobisisobutyronitrile (20 mg) and 2-phenylprop-2-yl dithiobenzoate (5)(60.7 mg) in benzene (5 mL) was prepared. Aliquots (4 mL) weretransferred to ampoules, degassed and sealed. The ampoules were heatedat 60° C. for the times indicated in the Table.

TABLE 1 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 60°C. Entry time/hr M_(n) M_(w)/M_(n) % Conv. M_(n) (calc) 1 2  9 800 1.2713.5  8 410 2 4 18 000 1.19 27.3 17 000 3 8 29 800 1.15 51.5 32 100 4 1656 200 1.12 95.0 59 200

Example 20 Preparation of low polydispersity poly(methyl acrylate) with1-phenylethyl dithiobenzoate (4)

Stock solutions (I) of azobisisobutyronitrile (6.6 mg) in benzene (50mL) and (II) of 1-phenylethyl dithiobenzoate (4) (87.6 mg) in benzene(50 mL) were prepared. Aliquots of stock solution (I) (2 mL) and stocksolution (II) (6 mL) were transferred to ampoules containing methylacrylate (2 mL) which were degassed, sealed and heated at 60° C. for thetimes specified in Table 2 below.

TABLE 2 Molecular weight and conversion data for poly(methyl acrylate)prepared with 1-phenylethyl dithiobenzoate (4) at 60° C. Entry time/hrM_(n) M_(w)/M_(n) % Conv. 1 20 13 500 1.11 26.2 2 64 28 800 1.13 52.9 3110 32 700 1.16 63.8

Example 21 Preparation of low polydispersity poly(n-butyl acrylate) with1-phenylethyl dithiobenzoate (4)

A stock solution (I) of azobisisobutyronitrile (13.4 mg) in benzene (50mL) and a stock solution (II) of 1-phenylethyl dithiobenzoate (4) (50.6mg) in benzene (50 mL) were prepared. Aliquots of solution (I) (10 mL)and solution (II) (20 mL) were added to a reaction vessel containingn-butyl acrylate (20 mL). The reaction mixture was degassed, sealed andheated at 60° C. for 2 hours, to give poly(n-butyl acrylate) (2.48 g,13.9% conversion) with M_(n) 33,600, M_(w) 37,800 and M_(w)/M_(n) 1.13.

Example 22 Preparation of low polydispersity poly(acrylic acid) using1-phenylethyl dithiobenzoate (4)

Stock solution (I) of azobisisobutyronitrile (6.64 mg) inN,N-dimethylformamide (DMF) (25 mL) and stock solution (II) of1-phenylethyl dithiobenzoate (4) (17.7 mg) in DMF (25 mL) were prepared.Aliquots of stock solution (I) (2 mL), stock solution (II) (6 mL) andacrylic acid (2 mL) were placed in a reaction vessel. The reactionmixture was degassed, sealed and heated at 60° C. for 4 hours. Afterremoval of the solvent and excess monomer, poly(acrylic acid) (0.37 g,17.5% conversion) was obtained. A portion was methylated(tetramethylammoniurn hydroxide (25% in methanol) and excess methyliodide) to give poly(methyl acrylate) of M_(n) 13792, M_(w) 16964 andM_(w)/M_(n) 1.23.

Example 23 Preparation of low polydispersity polystyrene via bulkpolymerization of styrene with benzyl dithiobenzoate (3)

A stock solution of styrene (60 mL) and azobisisobutyronitrile (16.9 mg)was prepared. Aliquots (5 mL) were removed and transferred to ampoulescontaining benzyl dithiobenzoate (11.4 mg). The ampoules were degassed,sealed and heated at 60° C. for the periods of time indicated in theTable below. The results are listed in Table 3 below.

TABLE 3 Molecular weight and conversion data for polystyrene preparedwith benzyl dithiobenzoate at 60° C. Entry time/hr M_(n) M_(w)/M_(n) %Conv. 1 1 164 000  1.83 1.61 (control) 2 1 1 500 1.36 0.68 3 2 2 2601.27 1.49 4 4 3 630 1.24 3.46 5 8 6 020 1.21 6.92 6 12 8 900 1.16 10.607 16 11 780  1.16 13.66 8 20 14 380  1.13 17.16 9 30 18 500  1.12 22.4310  50 25 200  1.17 31.82 11  100 33 400  1.13 42.32

Example 24 Preparation of low polydispersity polystyrene via bulkpolymerization of styrene using 2-phenylprop-2-yl dithiobenzoate (5)

Polystyrene was prepared under the conditions used for Example 5 with2-phenylprop-2-yl dithiobenzoate (5) (11.4 mg per ampoule) in place ofbenzyl dithiobenzoate. Results are shown in Table 4 below.

TABLE 4 Molecular weight and conversion data for polystyrene preparedwith 2-phenylprop-2-yl dithiobenzoate at 60° C. Entry time/hr M_(n)M_(w)/M_(n) % Conv. 1 1 285 000  1.63 1.67 (control) 2 1   833 1.12 0.493 4  4 510 1.09 3.74 4 20 21 500 1.14 19.45 5 50 40 000 1.17 37.49 6 10052 000 1.18 57.33

Example 25 Preparation of low polydispersity polystyrene via thermalpolymerization of styrene using 1-phenylethyl dithiobenzoate (4) at 100°C.

A stock solution of styrene (10 mL) and 1-phenylethyl dithiobenzoate (4)(24.8 mg) was prepared. Aliquots (2 mL) of this solution weretransferred to ampoules which were degassed, sealed and heated at 100°C. for the times indicated in Table 5 below and analyzed by GPC.

TABLE 5 Molecular weight and conversion data for polystyrene preparedwith 1-phenylethyl dithiobenzoate (4) at 100° C. Entry time/hr M_(n)M_(w) M_(w)/M_(n) % Conv. 1 6 227 000  434 000  1.91 21.7 (Control) 2 6 5 800  6 300 1.09 9.7 3 20 22 000 25 000 1.15 36.8 4 64 38 500 47 0001.22 70.6 5 120 50 000 61 000 1.23 91.9

Example 26 Preparation of low polydispersity polystyrene via thermalpolymerization of styrene using 1-phenylethyl dithiobenzoate (4) at 100°C.

Example 25 was repeated with a threefold higher concentration of1-phenylethyl dithiobenzoate (4) (75.6 mg) in the stock solution. Theresults are summarized in the Table 6 below.

TABLE 6 Molecular weight and conversion data for polystyrene preparedwith 1-phenylethyl dithiobenzoate (4) at 100° C. Entry time/hr M_(n)M_(w) M_(w)/M_(n) % Conv. 1 6  3 440 37 30  1.08 12.3 2 20 10 000 11 0001.08 35.0 3 64.5 22 000 24 000 1.10 65.6 4 120 27 000 31 000 1.16 87.6

Example 27 Preparation of low polydispersity polystyrene via thermalpolymerizations of styrene using 2-phenylprop-2-yl dithiobenzoate (5) at100° C.

Example 26 was repeated with 2-phenylprop-2-yl dithiobenzoate (5) inplace of 1-phenylethyl dithiobenzoate (4) (same molar concentration).The results are listed in Table 7.

TABLE 7 Molecular weight and conversion data for polystyrene preparedwith 2-phenylprop-2-yl dithiobenzoate (5) at 100° C. Entry time/hr M_(n)M_(w) M_(w)/M_(n) % Conv. 1 2  1 520  1 690 1.12 4.3 2 6  5 680  6 1401.08 14.3 3 20 13 800 14 900 1.08 39.9 4 64 25 000 28 100 1.12 81.0 5119 26 000 30 000 1.14 88.0

Example 28 Preparation of low polydispersity polystyrene via emulsionpolymerization of styrene using benzyl dithiobenzoate (3) at 80° C.

A 5-neck reaction vessel fitted with a stirrer, condenser andthermocouple was charged with water (75 g) and sodium dodecyl sulfate (5g of 10% aqueous solution). The mixture was degassed under nitrogen at80_C for 40 minutes. A solution of 4,4′-azobis(4-cyanopentanoic acid)(0.14 g) and benzyl dithiobenzoate (3) (0.215 g) in styrene (3.7 g) wasadded as a single shot. Further 4,4′-azobis(4-cyanopentanoic acid)(0.209 g) in sodium dodecyl sulfate (1% aq solution) (24 g) at a rate of0.089 mL/min along with styrene (32.9 g) at a rate of 0.2 mL/min wereadded by syringe pumps. On completion of the initiator feed, thereaction was held at 80_C for a further 90 minutes. The isolatedpolystyrene had M_(n) 53 200; M_(w)/M_(n) 1.37 at 73% conversion.

Example 29 Preparation of low polydispersity polystyrene via emulsionpolymerizations of styrene using benzyl dithiobenzoate (3) at 80° C.

Example 28 was repeated with a higher concentration of benzyldithiobenzoate (3) (0.854 g).

The isolated polystyrene had M_(n) 3 010; M_(w)/M_(n) 1.20 at 19%conversion.

Example 30 Preparation of low polydispersity poly(methylacrylate-block-ethyl acrylate)

A sample of poly(methyl acrylate) (0.17 g, M_(n) 24 070, M_(w)/M_(n)1-0.07) made with 1-phenylethyl dithiobenzoate (4) (as described inExample 20) was dissolved in ethyl acrylate (2 mL) and benzene (8 mL)containing azobisisobutyronitrile (0.52 mg). The vessel was degassed,sealed and heated at 60° C. for 2 hours to give poly(methylacrylate-block-ethyl acrylate) (0.22 g, 10.8% conversion), M_(n) 30 900,M_(w)/M_(n) 1.10.

Example 31 Preparation of low polydispersity poly(n-butylacrylate-block-acrylic acid)

A stock solution of azobisisobutyronitrile (6.64 mg) in DMF (25 mL) wasprepared. In an ampoule, poly(n-butyl acrylate) from Example 21, (0.5 g,M_(n) 33569, M_(w)/M_(n) 1.13) was dissolved in DMF (5.5 mL), acrylicacid (4 mL) and stock solution (0.5 mL). The mixture was degassed,sealed and heated at 60° C. for 2 hours. After removal of the solventand unreacted monomer, poly(n-butyl acrylate-block-acrylic acid) wasobtained (0.848 g, 8.3% conversion). GPC results (after methylation ofthe acrylic acid of the diblock): M_(n) 52 427; M_(w) 63 342;M_(w)/M_(n) 1.19.

Example 32 Preparation of low polydispersity polystyrene using benzyldithioacetate (12)

A stock solution of styrene (10 mL), benzyl dithioacetate (12) (17 mg)and azobisisobutyronitrile (2.8 mg) was prepared. Aliquots (2 mL) wereremoved and transferred to ampoules. The ampoules were degassed, sealedand heated at 60° C. for the periods of time indicated in Table 8 below.

TABLE 8 Molecular weight and conversion data for polystyrene preparedwith benzyl dithioacetate(12) at 60° C. Entry time/hr M_(n) M_(w)M_(w)/M_(n) % Conv. 1 2  6 840 11 800 1.72 1.8 2 4  8 570 13 500 1.585.0 3 16 19 000 25 000 1.32 16.5 4 40 30 000 37 000 1.24 28.9

Example 33 Preparation of low polydispersity poly(n-butyl acrylate)using benzyl dithiobenzoate (3)

Stock solution (I) of azobisisobutyronitrile (13.4 mg) in benzene (50mL) and stock solution (II) of benzyl dithiobenzoate (3) (9.62 mg) inbenzene (10 mL) were prepared.

Aliquots of stock solution (I) (2 mL) and stock solution (II) (4 mL)were transferred to ampoules already containing n-butyl acrylate (4 mL).The ampoules were degassed, sealed and heated at 60° C. for the periodsof time indicated in Table 9 below.

TABLE 9 Molecular weight and conversion data for poly(n-butyl acrylate)prepared with benzyl dithiobenzoate (3) at 60° C. M_(n) Entry time/hrM_(n) M_(w)/M_(n) (calc) % Conv. 1 2 26 000 1.12 25 866 11.4 2 8 92 0001.14 90 760 40.0

Example 34 Preparation of low polydispersity poly(N,N-dimethylacrylamide) using benzyl dithiobenzoate (3)

A stock solution (I) of azobisisobutyronitrile (2.5 mg) andN,N-dimethylacrylamide (10 mL) in benzene (50 mL) was prepared. Stocksolution (II) containing benzyl dithiobenzoate (3) (4 mg) in stocksolution (I) (20 mL) was prepared. Aliquots of stock solutions (I) and(II) were transferred to ampoules (in the quantities indicated in theTable below). The ampoules were degassed, sealed and heated at 60° C.for 1 hour. The molecular weight and polydispersity data are summarisedin Table 10 below.

TABLE 10 Molecular weight and conversion data for poly(N,N-dimethylacrylamide) prepared with benzyl dithiobenzoate (3) at 60° C. SolutionSolution Entry (I) (mL) (II) (mL) CTA (mg) M_(n) M_(w)/M_(n) M_(n)(calc) % Conv. 1 0 10 2  35 000 1.14  30 266 12.9 2 5 5 1 135 000 1.23120 597 25.7 3 7.5 2.5 0.5 224 000 1.44 293 742 31.3 4 10 0 0 833 0002.59 — 76.9 (control)

Example 35 Emulsion polymerization of styrene in the presence of benzyldithioacetate at 80° C. with sodium dodecyl sulfate as surfactant and4,4′-azobis(4-cyanopentanoic Acid) as initiator

A 5-neck reaction vessel fitted with a stirrer, condenser andthermocouple was charged with water (75 g) and sodium dodecyl sulfate (5g of 10% aqueous solution). The mixture was degassed under nitrogen at80° C. for 40 minutes. A solution of 4,4′-azobis(4-cyanopentanoic acid)(0.14 g) and benzyl dithioacetate (0.155 g) in styrene (3.7 g) was addedas a single shot. Further 4,4′-azobis(4-cyanopentanoic acid) (0.211 g)in sodium dodecyl sulfate (1% aq solution) (24 g) was added at a rate of0.089 mL/min along with styrene (32.9 g) at a rate of 0.2 mL/min.

On completion of the initiator feed, the reaction was held at 80_C for afurther 90 minutes. The results of the experiment are summarized inTable 11.

TABLE 11 Molecular weight and conversion data for polystyrene preparedwith benzyl dithioacetate in emulsion at 80° C. Reaction % Entrytime/min M_(n) M_(w)/M_(n) Conversion^(a) 1 75 21 000 1.27   97^(a) 2120 29 000 1.26   98^(a) 3 180 35 000 1.33 >99 4 240 37 000 1.35 >99 5270 38 000 1.34 >99 6 360 36 000 1.38 >99 ^(a)Instantaneous conversion(conversion of monomer added up to time of sampling).

Example 36 Preparation of narrow polydispersitypoly(styrene-block-N,N-dimethylacrylamide)

The polystyrene (M_(n) 20300, M_(w)/M_(n) 1.15) used in this experimentwas prepared by bulk polymerization of styrene (100 mL) at 60° C. for30.5 hours with azobisisobutyronitrile (28.17 mg) as initiator in thepresence of benzyl dithiobenzoate (3) (228 mg).

A solution of the above polystyrene (0.2 g), N,N-dimethylacrylamide (2mL), azobisisobutyronitrile (0.5 mg) and benzene (8 mL) was transferredto an ampoule. The resulting mixture was degassed, sealed and heated at60° C. for 1 hour. The volatiles were removed in vacuo to givepoly(styrene-block-dimethylacrylamide) at 0.4 g, 10.4% conversion, withM_(n) 43 000 and M_(w)/M_(n) 1.24.

Example 37 Preparation of low Polydispersitypoly(4-methylstyrene-block-styrene)

A mixture of polystyrene (0.5 g, M_(n) 20300, M_(w)/M_(n) 1.15, preparedas described in Example 36), 4-methylstyrene (2 mL),azobisisobutyronitrile (2.5 mg) and benzene (0.5 mL) were transferred toan ampoule. The resulting mixture was degassed, sealed and heated at 60°C. for 3 hours. Volatiles were removed under reduced pressure to givepoly(styrene-block-4-methylstyrene) (0.81 g, 17.1% conversion, M_(n) 25400 and M_(w)/M_(n) 1.19).

Example 38 Preparation of low polydispersity poly(methylmethacrylate-block-styrene)

Poly(methyl methacrylate) (M_(n) 17408, M_(w)/M_(n) 1.20) was preparedunder the conditions described for Example 19 with a reaction time of 4h. This polymer (1.7 g) was dissolved in ethyl acetate and the solutiontransferred to an ampoule. The ethyl acetate was removed under reducedpressure and azobisisobutyronitrile (2.82 mg) and styrene (10 mL) wereadded. The ampoule was degassed, sealed and heated at 60° C. for 20hours. After removal of the unreacted styrene, poly(methylmethacrylate-block-styrene) was obtained (3.9 g, 23.5% conversion) withM_(n) 35 000; M_(w) 44 000; M_(w)/M_(n) 1.24.

Example 39 Preparation of low polydispersity poly(n-butyl acrylate) viathe solution polymerization of n-butyl acrylate at 90° C. in thepresence of 1,4-bis(thiobenzoylthiomethyl)benzene (8)

A stock solution of 1,1′-azobis(1-cyclohexanecarbonitrile) (8.03 mg) inbenzene (10 mL) was prepared. Aliquots (1 mL) of the stock solution wereadded to ampoules containing n-butyl acrylate (4 mL),1,4-bis(thiobenzoylthiomethyl)benzene (8) (12.7 mg) and benzene (5 mL).The contents of the ampoules were degassed, sealed and heated at 90° C.for the times given in Table 12 below.

TABLE 12 Molecular weight and conversion data for poly(n-butylacrylate)prepared with 1,4-bis(thiobenzoylthiomethyl)benzene (8) at 90°C. Entry time/hr M_(n) M_(w)/M_(n) M_(n) (calc) % Conv. 1 1  5 090 1.21 5 079 4.4 2 5 57 000 1.32 65 571 56.8

Example 40 Preparation of low polydispersity poly(n-butyl acrylate) viathe solution polymerization of n-butyl acrylate at 90° C. in thepresence of 1,4-bis(2-thiobenzoylthioprop-2-yl)benzene (10)

Stock solution (I) of 1,1′-azobis(1-cyclohexanecarbonitrile) (10.09 mg)in benzene (25 mL), and stock solution (II) of1,4-bis(2-thiobenzoylthioprop-2-yl)benzene (10) (175.1 mg) in benzene(25 mL) were prepared. Aliquots of stock solution (I) (2 mL) and stocksolution (II) (4 mL) were added to ampoules containing n-butyl acrylate(4 mL). The ampoules were degassed, sealed and heated at 90° C. for thetimes shown in Table 13 below.

TABLE 13 Molecular weight and conversion data for poly(n-butylacrylate)prepared with 1,4-bis(2-thiobenzoylthioprop- 2-yl)benzene (10)at 90° C. Entry time/hr M_(n) M_(w)/M_(n) M_(n) (calc) % Conv. 1 5   9371.13   952 1.6 2 16 28 000 1.21^(a) 27 365 46.0 3 42 41 000 1.37^(a) 43904 73.8 ^(a)trimodal molecular weight distribution

Example 41 Preparation of low polydispersity star polystyrene via thethermal polymerization of styrene at 100° C. in the presence ofhexakis(thiobenzoylthiomethyl)benzene (7)

A stock solution comprising of styrene (10 mL) andhexakis(thiobenzoylthiomethyl)benzene (7) (48.9 mg) was prepared.Aliquots of the stock solution (2 mL) were transferred to ampoules whichwere degassed, sealed and heated at 100° C. for the times given in Table14 below.

TABLE 14 Molecular weight and conversion data for star polystyreneprepared with hexakis(thiobenzoylthiomethyl)benzene (7) at 100° C. Entrytime/hr M_(n) M_(w) M_(w)/M_(n) % Conv. 1 6  1 350  1 530 1.13 0.33 2 2034 100  46 500 1.36 27.5 3 64 80 000 133 000 1.67 72.1

Example 42 Preparation of low polydispersity star polystyrene via thethermal polymerization of styrene at 100° C. in the presence of1,2,4,5-tetrakis-(thiobenzoylthiomethyl)benzene (9)

A stock solution of styrene (10 mL) and1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene (9) (54.5 mg) wasprepared. Aliquots (2 mL) of the stock solution were transferred toampoules which were degassed, sealed and heated at 100° C. for the timesgiven in the Table below. Polymer was obtained by removal of thevolatiles. The results are summarized in Table 15 below.

TABLE 15 Molecular weight and conversion data for star polystyreneprepared with 1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene (9) at 100°C. M_(n) Entry time/hr M_(n) M_(w) M_(w)/M_(n) (calc) % Conv. 1 6   989 1 100 1.11 — 0.88 2 20 26 000 31 100 1.20 27 257 22.0 3 64 67 500 87600 1.30 90 814 73.3

Example 43 Preparation of low polydispersity star polystyrene via thethermal polymerization of styrene at 120° C. in the presence of1,2,4,5-tetrakis-(thiobenzoylthiomethyl)benzene (9)

A stock solution of styrene (10 mL) and1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene (9) (54.5 mg) wasprepared. Aliquots (2 mL) of the stock solution were transferred toampoules which were degassed, sealed and then heated at 120° C. for thetimes given below. The polymer was isolated by removal of the volatiles.The results are summarized in Table 16 below.

TABLE 16 Molecular weight and conversion data for star polystyreneprepared with 1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene (9) at 120°C. Entry time/hr M_(n) M_(w) M_(w)/M_(n) M_(n) (calc) % Conv. 1 6 43 000 55 000 1.29 51416 41.5 2 20 75 000 109 000 1.44 100353 81.0 3 64 80 000119 000 1.49 109770 88.6

Example 44 Preparation of low polydispersity poly(methyl methaerylate)using 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate (14)

The method of Example 19 was used with 2-(ethoxycarbonyl)prop-2-yldithiobenzoate (14) (same molar concentrations). Results are summarizedin Table 17 below.

TABLE 17 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate(14) at 60° C. Entry time/hr M_(n) M_(w)/M_(n) % Conv. 1 2 30 000 1.8922.7 2 4 35 000 1.72 37.1 3 8 40 000 1.66 67.4 4 16 53 000 1.48 >95

Example 45 Preparation of low polydispersity poly(methyl methacrylate)with 2-cyanoprop-2-yl dithiobenzoate (15)

The method of Example 19 was used with 2-cyanoprop-2-yl dithiobenzoate(15) (same molar concentrations). Results are summarized in Table 18below.

TABLE 18 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-cyanoprop-2-yl dithiobenzoate (15) at 60°C. Entry time/hr M_(n) M_(w)/M_(n) % Conv. 1 2  9 200 1.26 16.2 2 4 17000 1.19 39.4 3 8 30 000 1.17 68.6 4 16 52 000 1.16 >90

Example 46 Preparation of low polydispersity poly(methyl methacrylate)using 2-(4-chlorophenyl)prop-2-yl dithiobenzoate (18)

The experimental conditions described in Example 19 (same molarconcentrations) were used to prepare low polydispersity poly(methylmethacrylate) with 2-(4-chlorophenyl)prop-2-yl dithiobenzoate (18).Results are summarized in Table 19 below.

TABLE 19 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-(4-chlorophenyl)propyl dithiobenzoate (18)at 60° C. Entry time/hr M_(n) M_(w)/M_(n) % Conv. M_(n) (calc) 1 2  8840 1.25 15.1  9 390 2 4 16 200 1.17 31.0 19 330 3 8 30 400 1.13 63.3 39260 4 16 52 800 1.14 >95 59 205

Example 47 Preparation of low polydispersity poly(methyl methacrylate)with tert-butyl trithioperbenzoate (21)

The experimental conditions described in Example 19 (same molarconcentrations) were used to prepare low polydispersity poly(methylmethacrylate) with tert-butyl trithioperbenzoate (21). After heating at60° C. for 16 hours, poly(methyl methacrylate) was obtained (62.8%conversion; Mn 92 000; M_(w)/M_(n) 1.34).

Example 48 Preparation of low polydispersity poly(methyl methacrylate)with 2-phenylprop-2-yl 4-chlorodithiobenzoate (22)

The experimental conditions described in Example 19 (same molarconcentrations) were used to prepare low polydispersity poly(methylmethacrylate) with 2-phenylprop-2-yl 4-chlorodithiobenzoate (22). Afterheating at 60° C. for 16 hours, poly(methyl methacrylate) was obtained(95% conversion; Mn 55 000; M_(w)/M_(n) 1.07).

Example 49 Preparation of low polydispersity poly(methyl methacrylate)with 2-phenylprop-2-yl 1-dithionaphthalate (23)

The experimental conditions described in Example 19 (same molarconcentrations) were used to prepare low polydispersity poly(methylmethacrylate) with 2-phenylprop-2-yl 1-dithionaphthalate (23). Afterheating at 60° C. for 16 hours, poly(methyl methacrylate) was obtained(95% conversion; Mn 57500; M_(w)/M_(n) 1.10).

Example 50 Preparation of low polydispersity poly(methyl methacrylate)in presence of 2-phenylprop-2-yl dithiobenzoate (5) with benzoylperoxide as initiator

A stock solution containing methyl methacrylate (20 mL), benzoylperoxide (24.2 mg) and benzene (5 mL) was prepared. An aliquot (5 mL) ofthe stock solution was removed and 4 mL of this was placed in an ampoulelabelled as control run (entry 1). 2-phenylprop-2-yl dithiobenzoate (5)(54.5 mg) was added to the remaining 20 mL of stock solution. Aliquotsof this solution (4 mL) were transferred to four ampoules which weredegassed, sealed and heated at 60_C. The results are summarized in Table20 below.

TABLE 20 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 60°C. Entry time/hr M_(n) M_(w)/M_(n) % Conv. 1 (control) 2 453 000  1.8111.1 2 2  6 080 1.40 6.8 3 4 10 300 1.28 14.8 4 8 20 000 1.17 33.4 5 1641 000 1.13 77.9The following example shows that polymerizations can be successfullycarried out in both polar and nonpolar solvents.

Example 51 Preparation of low molecular weight and low polydispersitypoly(methyl methacrylate) using 2-phenylprop-2-yl dithiobenzoate (5) insolvents such as benzene or 2-butanone (MEK)

Stock solutions were prepared by adding methyl methacrylate (15 mL) andazobisisobutyronitrile (100 mg) to the required solvent (5 mL). Aliquots(10 mL) of each stock solution and appropriate amount of2-phenylprop-2-yl dithiobenzoate (5) (see Table 23) were transferred toampoules which were degassed and heated at 60° C. for specified times.Results are summarized in Table 21 below.

TABLE 21 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 60°C. in various solvents Dithioester (g) Time (hr) Solvent M_(n)M_(w)/M_(n) % Conv. 1.00 63.58 Benzene 3 200 1.17 79.8 0.40 24 Benzene 6600 1.21 95.0 1.00 63.58 2-butanone 2 800 1.17 61.3 0.40 24 2-butanone 6300 1.19 90.2

Example 52 Solution polymerization of methyl methacrylate (25%) with2-phenylprop-2-yl dithiobenzoate (5)

A series of methyl methacrylate polymerizations were carried out with2-phenylprop-2-yl dithiobenzoate (5). The results (see Table 24) whencompared with control experiments clearly indicate that in the presenceof dithioester there is some retardation (conversions are ca. 10% lessfor the same reaction time). A stock solution containing methylmethacrylate (10 mL), benzene (30 mL) and azobisisobutyronitrile (40 mg)was prepared. The stock solution was divided into two 20 mL portions.The first 20 mL portion was used for the ‘control’ experiments (entries1-4). 2-phenylprop-2-yl dithiobenzoate (5) (100 mg) was added to thesecond 20 mL portion (entries 5-8). Aliquots (4 mL) of these solutionswere transferred to ampoules which were degassed, sealed and heated at60° C. for the specified period of time.

Results are summarized in Table 22 below.

TABLE 22 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 60°C. in benzene control with CTA Entry time/hr parameter (no CTA) (5) 1 2M_(n) 98400 2880 M_(W)/M_(n) 1.83 1.31 % Conv. 20.3 10.7 2 4 M_(n) 885004570 M_(W)/M_(n) 1.84 1.24 % Conv. 35.3 23.5 3 16 M_(n) 69800 9250M_(W)/M_(n) 1.86 1.29 % Conv. 82.3 71.6 4 30 M_(n) 58400 11720M_(W)/M_(n) 1.91 1.25 % Conv. 95.0 88.7

Example 53 Preparation of low polydispersity polystyrene via bulkpolymerization of styrene using 2-(ethoxycarbonyl)prop-2-yldithiobenzoate (14)

A stock solution of azobisisobutyronitrile (14.08 mg) in styrene (50 mL)was prepared. Aliquots (5 mL) of the stock solution were transferred toampoules containing 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate (14)(11.26 mg) which were degassed and sealed under vacuum. The ampouleswere heated at 60° C. for periods of time indicated in Table 23 below.

TABLE 23 Molecular weight and conversion data for polystyrene preparedwith 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate (14) at 60° C. Entrytime/hr M_(n) M_(w)/M_(n) % Conv. 1 2 1 630 1.13 1.90 2 4 3 500 1.124.02 3 20 24 200  1.15 26.35

Example 54 Preparation of low polydispersity polystyrene via bulkpolymerization of styrene using 2,4,4-trimethylpent-2-yl dithiobenzoate(17)

Example 53 was repeated with the exception that the dithioester used was2,4,4-trimethylpent-2-yl dithiobenzoate (17) (same molarconcentrations). The results are summarized in Table 24 below.

TABLE 24 Molecular weight and conversion data for polystyrene preparedwith 2,4,4-trimethylpent-2-yl dithiobenzoate (17) at 60° C. Entrytime/hr M_(n) M_(w)/M_(n) % Conv. 1 2   495 1.13 0.57 2 4  1 180 1.141.28 3 20 17 400 1.19 18.55

Example 55 Preparation of low polydispersity polystyrene via thermalpolymerization of styrene with S-benzyl diethoxyphosphinyldithioformate(20)

A stock solution of styrene (10 mL) and S-benzyldiethoxyphosphinyldithioformate (20) (30.9 mg) was prepared. Aliquots (2mL) of the stock solution were transferred to ampoules which weredegassed and sealed. The first three ampoules (Table 25, entries 1-3),were heated at 100° C. and the final ampoule (Table 25, entry 4), washeated at 120° C. Samples were removed at the time intervals indicatedin the Table below and analyzed by GPC. The molecular weight increasedlinearly with % conversion and narrow, polydispersities are maintainedthroughout the polymerization.

TABLE 25 Molecular weight and conversion data for polystyrene preparedwith benzyldiethoxyphosphinyldithioformate (20) at 100° C. Entry Time/hrM_(n) M_(w)/M_(n) % Conv. 1^(a) 6 15 900 1.11 12.1 2^(a) 20 46 100 1.1338.0 3^(a) 64 79 300 1.25 77.8 4^(b) 22 73 500 1.37 88.9 ^(a)Entries1-3: The polymerizations were conducted at 100° C. ^(b)Entry 4: Thepolymerization was conducted at 120° C.

Example 56 Preparation of low polydispersity polystyrene via thermalpolymerization of styrene at 110° C. with 2-phenylprop-2-yldithiobenzoate (5)

Example 27 was repeated with the exception that the reaction temperatureused was 110° C. instead of 100° C. After 16 hours at 110° C.,polystyrene (55% conversion) with M_(n) 14 400 and M_(w)/M_(n) 1.04 wasobtained.

The following two Examples demonstrate the use of the invention toprepare polymers with functional end groups (e.g. carboxylic acid).

Example 57 Preparation of low polydispersity polystyrene via thermalpolymerization of styrene with carboxymethyl dithiobenzoate (27)

A stock solution of styrene (2 mL) and carboxymethyl dithiobenzoate (27)(24.8 mg) was prepared. Aliquots (1 mL) were transferred to two ampouleswhich were degassed, sealed and heated at 100° C. The results aresummarized in Table 26 below.

TABLE 26 Molecular weight and conversion data for polystyrene preparedwith carboxymethyl dithiobenzoate (27) at 100° C. Entry time/hr M_(n)M_(w)/M_(n) % Conv. 1 6 3 900 1.49 11.4 2 64 7 400 1.34 42.5

Example 58 Preparation of low polydispersity polystyrene via thermalpolymerization of styrene with 4-cyano-4-(thiobenzoylthio)pentanoic acid(24)

A stock solution of styrene (2 mL) and4-cyano-4-(thiobenzoylthio)pentanoic acid (24) (32.8 mg) was prepared.Aliquots (1 mL) were transferred to two ampoules which were degassed,sealed and heated at 100° C. The ¹³C-nmr spectrum of the isolatedpolymer (M_(n) 2,500; M_(w)/M_(n) 1.05) had a signal at d 177.7 ppmindicating the presence of carboxy end-group at one end of thepolystyrene. In addition, evidence from both ¹H-nmr and ¹³C-nmr spectraindicate the presence of thiobenzoylthio end group. The results aresummarized in Table 27 below.

TABLE 27 Molecular weight and conversion data for polystyrene preparedwith 4-cyano-4-(thiobenzoylthio)pentanoic acid (24) at 100° C. Entrytime/hr M_(n) M_(w)/M_(n) % Conv. 1 6 2 500 1.05 19.7 2 64 8 900 1.0561.3

Example 59 Preparation of low polydispersity polystyrene via thermalpolymerization of styrene with dibenzyl trithiocarbonate (26)

A stock solution comprising of styrene (5 g) and dibenzyltrithiocarbonate

(26) (43 mg) was prepared. Aliquots of the stock solution (2 g) weretransferred to two ampoules which were degassed, sealed, and heated at110° C. The results are summarized in Table 28 below.

TABLE 28 Molecular weight and conversion data for polystyrene preparedwith dibenzyl trithiocarbonate (26) at 110° C. Entry time/hr M_(n)M_(w)/M_(n) % Conv. 1 6 11,000 1.21 54 2 16 17,000 1.15 81

Example 60 Preparation of low polydispersity poly(n-butyl acrylate)using tert-butyl trithioperbenzoate (21)

Stock solution (I) of azobisisobutyronitrile (13.4 mg) in benzene (50mL) and stock solution (II) of tert-butyl trithioperbenzoate (21) (23.8mg) in benzene (25 mL) were prepared.

Aliquots of stock solution (I) (2 mL) and stock solution (II) (4 mL)were transferred to ampoules containing n-butyl acrylate (4 mL). Theampoules were degassed, sealed and heated at 60° C. for the timesindicated in the Table 29 which also shows the results of the polymerproduced.

TABLE 29 Molecular weight and conversion data for poly(n-butyl acrylate)prepared with tert-butyl trithiophenylperformate (21) at 60° C. Entrytime/hr M_(n) M_(w)/M_(n) % Conv. 1 2  12 700 1.12 6.8 2 8  78 000 1.0740.5 3 16 118 000 1.14^(a) 61.2 4 40 174 000 1.24^(a) 81.7 ^(a)Bimodalmolecular weight distribution, with a small high molecular weightshoulder.

Example 61 Preparation of low polydispersity poly(N,N-dimethylaminoethylmethacrylate) using 2-phenylprop-2-yl dithiobenzoate (5)

Stock solution (I) of azobisisobutyronitrile (20 mg) andN,N-dimethylaminoethyl methacrylate (15 mL) in benzene (5 mL) and stocksolution (II) consisting of stock solution (I) (18 mL) and2-phenylprop-2-yl dithiobenzoate (5) (61.1 mg) were prepared. Theremainder of stock solution (I) (2 mL) was used for the controlexperiment. Aliquots of stock solution (II) (4 mL) were transferred toampoules and degassed, sealed and heated at 60° C. for the timesindicated in Table 30.

TABLE 30 Molecular weight and conversion data for poly(N,N-dimethylaminoethyl methacrylate) prepared with 2-phenylprop-2-yldithiobenzoate (5) at 60° C. Entry time/hr M_(n) M_(w)/M_(n) % Conv. 1(Control) 2 13 000 40.2^(a) 45.6 2 2 11 600 1.19 30.2 3 4 15 900 1.1949.6 4 16 28 000 1.21 91.9 ^(a)Multimodal molecular weight distribution

Example 62 Preparation of low polydispersity poly(vinyl benzoate) using2-cyanoprop-2-yl dithiobenzoate (15)

Stock solution (I) was prepared by dissolving2,2′-azobis(2-methylpropane) (10 mg) in vinyl benzoate (10 mL). Stocksolution (II) was prepared by dissolving 2-cyanoprop-2-yl dithiobenzoate(15) (160 mg) in vinyl benzoate (10 mL). A mixture comprising stocksolution (I) (0.14 mL), stock solution (II) (2.75 mL) and vinyl benzoate(3 g) was added to an ampoule. The ampoule was degassed, sealed andheated at 150° C. for 48 hours. The resultant viscous liquid was reducedin vacuo to poly(vinyl benzoate). M_(n) 3 490, M_(w) 4 500, M_(w)/M_(n)1.29, 25% conversion.

Example 63 Preparation of low polydispersity poly(vinyl butyrate) using2-cyanopropyl dithiobenzoate (15)

Stock solution (I) was prepared by dissolving2,2′-azobis(2-methylpropane) (10 mg) in vinyl butyrate (101 mL). Amixture comprising of stock solution (I) (0.14 mL), 2-cyanoprop-2-yldithiobenzoate (15) (50 mg) and vinyl butyrate (5.9 g) was added to anampoule. The ampoule was degassed, sealed and heated at 150° C. for 48hours. The resultant viscous liquid was reduced in vacuo to poly(vinylbutyrate). M_(n) 1 051, M_(w) 1 326, M_(w)/M_(n) 1.26, 5% conversion.

Example 64 Preparation of low polydispersity poly(p-styrenesulfonic acidsodium salt) using sodium salt of 4-cyano-4(thiobenzoylthio)pentanoicacid

A stock solution of 4,4′-azobis(4-cyanopentanoic acid) (23.4 mg) and pstyrenesulfonic acid sodium salt (4.99 g) in distilled water (25 mL) wasprepared. An aliquot of the stock solution (10 mL) was transferred to aconical flask containing sodium salt of4-cyano-4-(thiobenzoylthio)pentanoic acid (50 mg). This solution wasdivided into two equal parts and transferred to two ampoules. A controlexperiment was carried out by placing an aliquot (5 mL) of the stocksolution to another ampoule. The ampoules were degassed, sealed andheated at 70° C. for the periods of time indicated in Table 31 below.

TABLE 31 Molecular weight and conversion data for poly(p-styrenesulfonicacid sodium salt) prepared with 4-cyano-4-(thiobenzoylthio)pentanoicacid at 70° C. in aqueous solution Entry time/hr M_(n) ^(a) M_(w)/M_(n)% Conv.^(b) 1 (control) 1 73 000 2.27 96.0 2 4  8 000 1.13 73.4 3 14.2510 500 1.20 84.1 ^(a)GPC molecular weight in polystyrene sulfonic acidsodium salt standard equivalents. Operation conditions: columns, Waters'Ultrahydrogel 500, 250 and 120; eluent, 0.1 M sodium nitrate/acetontrile(80:20); flow rate, 0.8 mL/min.; detector, Waters 410 RI; injectionsize, 0.25 mg/50 mL. ^(b)% Conversion was estimated by ¹H-nmr.The following example illustrates narrow polydispersity cyclopolymersynthesis.

Example 65 Preparation of low polydispersity cyclopolymer of2,4,4,6-tetrakis(ethoxycarbonyl)-1,6-heptadiene using 2-phenylprop-2-yldithiobenzoate (5)

A mixture of 2,4,4,6-tetrakis(ethoxycarbonyl)-1,6-heptadiene (1.05 g),2-phenylprop-2-yl dithiobenzoate (5) (24.5 mg), azobisisobutyronitrile(4.5 mg) and o-xylene (3 mL) were added to an ampoule degassed andsealed. The ampoule was heated at 60° C. for 64 hours. After removal ofall the volatiles, the cyclopolymer was isolated (0.70 g, 66.7%conversion) with Mn 6540, M_(w) 8920, and polydispersity 1.36. In theabsence of dithiobenzoate (5), the corresponding cyclopolymer wasisolated (88% conversion) with M_(n) 23 400, M_(w) 47 200, andM_(w)/M_(n) 2.01.

The following two examples demonstrate the preparation of copolymers.

Example 66 Preparation of low polydispersity poly(methylmethacrylate-co-styrene) in the presence of 2-phenylprop-2-yldithiobenzoate (5)

A series of copolymerizations of styrene/methyl methacrylate (52:48 moleratio) in the presence of 2-phenylprop-2-yl dithiobenzoate (5) wascarried out. The experimental conditions were similar to those describedby O'Driscoll and Huang [Eur. Polym. J., 25(7/8), 629, (1989); ibid,26(6), 643, (1990)]. Aliquots (5 mL) of styrene/methyl methacrylate(52:48 mole ratio) were transferred to eight ampoules containingdimethyl 2,2′-azobisisobutyrate (11.5 mg) four of which containedphenylprop-2-yl dithiobenzoate (5) (76.4 mg). The ampoules weredegassed, sealed and placed in a constant temperature bath at 60° C.After the specified time (see Table), the polymerizations were quenchedby cooling the ampoule in cold water and the polymer was isolated byremoval of all the volatiles. Results are summarized in Table 32 below.

TABLE 32 Molecular weight and conversion data for poly(methylmethacrylate-co-styrene) prepared with 2-phenylprop-2-yl dithiobenzoate(5) at 60° C. control with CTA Entry time/hr parameter (no CTA) (5) 1 5M_(n) 123 200 10 100 M_(W)/M_(n)      1.67     1.21 % Conv.     16.8    9.9 2 10 M_(n) 125 900 20 200 M_(W)/M_(n)      1.75     1.17 % Conv.    32.2    22.8 3 15 M_(n) 148 800 26 900 M_(W)/M_(n)      1.82     1.22 %Conv.     46.9    34.2 4 20 M_(n) 257 000 33 800 M_(W)/M_(n)      2.39    1.21 % Conv.     91.2    43.1

Example 67 Preparation of low polydispersitypoly(acrylonitrile-co-styrene) in the presence of 2-phenylprop-2-yldithiobenzoate (5)

A stock solution consisting of styrene (7.27 g) and acrylonitrile (2.27g) was prepared. An aliquot (2 g) of the stock solution was reserved forthe control experiment and 2-phenylprop-2-yl dithiobenzoate (5) (28.5mg) was added to the remaining stock solution. Aliquots of this solution(2 g) were transferred to ampoules which were degassed, sealed andheated at 100° C. for the times indicated in Table 33 below.

TABLE 33 Molecular weight and conversion data for poly(acrylonitrile-co-styrene) prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 100° C.Entry time/hr M_(n) M_(w)/M_(n) % Conv. 1 (control) 18 424 000  1.7096.0 2 4 20 100 1.04 26.0 3 8 33 000 1.05 42.0 4 18 51 400 1.07 70.7The following example illustrates synthesis of a quaternary copolymer.

Example 68 Preparation of low polydispersity quaternary copolymers ofMMA/iBMA/HEMA/Styrene in the presence of 2-phenylprop-2-yldithiobenzoate

A stock solution was prepared comprising methyl methacrylate (1.5 g),isobutyl methacrylate (3.38 g), hydroxyethyl methacrylate (1.5 g),styrene (1.13 g), 2-butanone (2 g), azobisisobutyronitrile (0.05 g) and2-phenylprop-2-yl dithiobenzoate (5) (0.163 g). Aliquots (4.5 g) of thestock solution were placed into ampoules which were degassed, sealed andheated at 60° C. for 1 and 24 hours. The quaternary copolymer wasisolated by evaporation and characterized by GPC analysis. Results aresummarized in Table 34 below.

TABLE 34 Molecular weight and conversion data for poly(hydroxethylmethacrylate-co-isobutyl methacrylate-co-methyl methacrylate-co-styrene)prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 60° C. % Entrytime/hr M_(n) M_(w)/M_(n) Conversion 1 1   633 1.23 — 2 24 11 300 1.47>99

Example 69 Preparation of low polydispersity styrene-butadiene polymersusing 1-phenylethyl dithiobenzoate (4)

This example was carried out to demonstrate that it is possible toprepare low polydispersity styrene/butadiene (SBR, 30:70) copolymerswith 1-phenylethyl dithiobenzoate (4) as chain transfer agent.

A mixture of styrene (36 g), water (197.6 g), potassium rosin soap (6.26g), sodium formaldehyde sulfoxylate (0.060 g), tri-potassium phosphate(0.293 g), sodium carbonate (0.036 g), potassium persulfate (0.366 g)and chain transfer agent (1-phenylethyl dithiobenzoate (4) (0.09 g) ortert-dodecyl mercaptan (0.191 g)) was placed in a 7 oz glass bottlecontaining crown seal with nitrile gaskets. The bottle was degassed bypurging with nitrogen, and then added butadiene (84 g). Thepolymerization was carried out at 50° C. and after 8 hours, SBRcopolymers were obtained having M_(w)/M_(n) of 1.17 when dithioester (4)was used as the chain transfer agent, and M_(w)/M_(n) 2.08 whentert-dodecyl mercaptan was used as chain transfer agent. Someretardation is observed with respect to the control polymerization.

Example 70 Preparation of low polydispersity block copolymers of methylmethacrylate and methacrylic acid in the presence of 2-phenylprop-2-yldithiobenzoate

To a reaction vessel, azobisisobutyronitrile (10 mg) and a poly(methylmethacrylate) sample (1 g, made with the use of 2-phenylprop-2-yldithiobenzoate (5) (M_(n) 3231, M_(w)/M_(n) 1.17), see Example 51) weredissolved in N,N-dimethylformamide (4.1 mL) and added to methacrylicacid (0.8 g). The ampoule was degassed, sealed and heated at 60° C. for16 hours. After removal of solvent, poly(methylmethacrylate-block-methacrylic acid) was obtained (near quantitativeconversion). GPC results obtained after methylation of the diblock, gavepolymer of M_(n) 4718 and M_(w)/M_(n) 1.18.

The following two examples illustrate the synthesis of triblockcopolymers from a bifunctional chain transfer agent. In the first step,a linear polymer with thiobenzoylthio groups at each end is prepared.The second step provides an ABA triblock.

Example 71 Preparation of poly(styrene-block-methylmethacrylate-block-styrene) in the presence of1,4-bis(2-thiobenzoylthioprop-2-yl)benzene (10)

Step 1: Preparation of low polydispersity poly(methyl methacrylate) witha dithioester group at each end

A stock solution (I) of azobisisobutyronitrile (20.26 mg) and methylmethacrylate (15 mL) in benzene (5 mL) was prepared. An aliquot of stocksolution (I) (2 mL) was transferred to an ampoule and was used as acontrol experiment. 1,4-Bis(2-thiobenzoylthioprop-2-yl)benzene (10)(93.64 mg) was added to the remaining stock solution (I) to form stocksolution (II). Aliquots (4 mL) of the stock solution (II) weretransferred into ampoules which were degassed, sealed and heated at 60°C. for the times indicated. The results are summarized in Table 35below.

TABLE 35 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 1,4-bis(2-thiobenzoylthioprop-2- yl)benzene(10) at 60° C. Entry time/hr M_(n) M_(w)/M_(n) % Conv. 1 2  5 400 1.329.8 2 4 12 200 1.22 23.3 3 8 23 600 1.18 49.9 4 16 45 800 1.15 98.5Step 2: Preparation of poly(styrene-block-methylmethacrylate-block-styrene)

The 8 hour poly(methyl methacrylate) sample (1.55 g, M_(n) 23 600,M_(w)/M_(n) 1.18) was dissolved in ethyl acetate and transferred to anampoule. The solvent was removed under reduced pressure andazobisisobutyronitrile (3.1 mg) and styrene (10 mL) were added. Theresulting solution was degassed, sealed and heated at 60° C. for 20hours. After removal of all the volatiles, the title block copolymer(orange pink colour foam) was isolated (3.91 g, 26% conversion), M_(n)59 300, M_(w)/M_(n) 1.76 (trimodal).

Example 72 Preparation of poly(hydroxyethyl methacrylate-block-methylmethacrylate-block-hydroxyethyl methacrylate) in the presence of1,4-bis(2-thiobenzoylthioprop-2-yl)benzene (10)

Step 1: Preparation of low polydispersity poly(methyl methacrylate) witha dithioester group at each end

Stock solution (I) consisting of azobisisobutyronitrile (20 mg) andmethyl methacrylate (15 mL) in benzene (5 mL) was prepared. Thissolution (18 mL) was transferred to an ampoule containing1,4-bis(2-thiobenzoylthioprop-2-yl)benzene (10) (93.5 mg) which was thendegassed, sealed and heated at 60° C. for 8 hours. The poly(methylmethacrylate) obtained (4.7 g, 33.5% conversion) had M_(n) 23 000 andM_(w)/M_(n) 1.16.

Step 2: Preparation of narrow polydispersitypoly(7-hydroxyethylmethacrylate-block-methyl methacrylate-block-hydroxyethyl methacrylate)

A solution of poly(methyl methacrylate) (1.74 g, M_(n) 23 000,M_(w)/M_(n) 1.16) in tetrahydrofuran (14 mL), hydroxyethyl methacrylate(1 mL) and azobisisobutyronitrile (10 mg) were transferred to an ampoulewhich was then degassed, sealed and heated at 60° C. for 4 hours. Theproduct poly(hydroxyethyl methacrylate-block-methylmethacrylate-block-hydroxyethyl methacrylate) (40.2% conversion) hadM_(n) 28 500 and M_(w)/M_(n) 1.18.

The following example illustrates the synthesis of star block copolymerswith a soft inner core (n-butyl acrylate) and hard outer shell(styrene).

Example 73 Preparation of star block copolymers of n-butyl acrylate andstyrene using 1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene (9)

Step 1: Star Polymers of n-Butyl Acrylate

Stock solution (I) of 2,2′-Azobis(2,4,4-trimethylpentane) (VR-110) (8mg) in benzene (25 mL) and stock solution (II) of1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene (9) (75 mg) in benzene(10 mL) were prepared. n-Butyl acrylate (4 mL), stock solution (I) (3mL) and stock solution (II) (3 mL) were transferred to an ampoule whichwas degassed, sealed and heated at 110° C. for 67 hours to give starpoly(n-butyl acrylate) (39.4% conversion), M_(n) 23 250, M_(w)/M_(n)2.22.

Step 2: Star Block Copolymers of n-Butyl Acrylate and Styrene

The star poly(n-butyl acrylate) (0.5 g, M_(n) 23248, M_(w)/M_(n) 2.22)and styrene (2 mL) were transferred into an ampoule degassed, sealed andheated at 110° C. for 16 hours. After removal of all the volatiles, thestar block copolymer was obtained (1.3 g, 71.4% conversion) with M_(n)82 500 and M_(w)/M_(n) 2.16.

The following example demonstrates the synthesis of a graft copolymerbased on the use of a polymer chain with pendant dithioester groups.

Example 74 Preparation of graft copolymers in the presence of 3- &4-vinylbenzyl dithiobenzoates (19)

Step 1: Poly(methyl methacrylate-co-vinylbenzyl dithiobenzoate)

A solution of vinylbenzyl dithiobenzoate (19) (100 mg, mixture of metaand para isomers), azobisisobutyronitrile (15 mg), methyl methacrylate(10 mL) in 2-butanone (10 mL) was placed in an ampoule, degassed, sealedand heated at 60° C. for 6 hours to give poly(methylmethacrylate-co-vinylbenzyl dithiobenzoate) (3.52 g, 37.6% conversion).GPC: M_(n) 102 000, M_(w)/M_(n) 2.26.

¹H-nmr analysis indicates an average of 3.5 thiobenzoylthio groups perpolymer chain.

Step 2: Poly(methyl methacrylate-graft-styrene)

A degassed solution of the poly(methyl methacrylate-co-vinylbenzyldithiobenzoate) from step 1 (0.5 g) and azobisisobutyronitrile (1.0 mg)in freshly distilled styrene (5.0 mL) was heated at 60° C. for 40 hours.The polymerization gave a red gel which was insoluble in THF, acetoneand chloroform. The finding that polystyrene homopolymer could not beextracted from the mixture indicates the success of the graftingexperiment.

Example 75 Preparation of low polydispersity poly(methyl methacrylate)by emulsion polymerization at 80° C. in the presence of2-phenylprop-2-yl dithiobenzoate (5)

A 5-necked reaction vessel fitted with a condenser, thermocouple, andmechanical stirrer was charged with water (14.8 g), sodium dodecylsulfate (3.0 g of 10% aqueous solution) and 2-phenylprop-2-yldithiobenzoate (5) (0.325 g) and the mixture degassed under nitrogen at90° C. for 50 minutes. Feeds of methyl methacrylate (37.5 mL, 0.316mL/min) and 4,4′-azobis(4-cyanopentanoic acid) (900 mg) in water (85 g,0.312 mL/min) were then commenced. After 65 min the concentration of theinitiator feed was involved [4,4′-azobis(4-cyanopentanoic acid) (450 mg)in water (94 g, 0.312 mL/min)]. On completion of the feeds, the reactionwas held at 90° C. for a further 90 minutes. The reaction mixture wassampled periodically to provide samples for GPC analysis (see Table 36below).

TABLE 36 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 90°C. in emulsion MMA Entry added (mL) M_(n) M_(w) M_(w)/M_(n) % Conv 120.5  3 550  4 530 1.27 14.2 2 37.5 12 000 15 800 1.32 41.4 3 final 26000 34 900 1.33 89.8The following three examples demonstrate the ‘one-pot’ synthesis ofblock copolymers by sequential monomer addition.

Example 76 Preparation of poly(methyl methacrylate-block-styrene) byemulsion polymerization at 80° C. in the presence of 2-phenylprop-2-yldithiobenzoate (5)

A 5-necked reaction vessel fitted with a condenser, thermocouple, andmechanical stirrer was charged with water (37.5 g) and sodium dodecylsulfate (3 g of 10% aqueous solution). The mixture was degassed at 80°C. under nitrogen for 40 minutes and a solution of4,4′-azobis(4-cyanopentanoic acid) (71 mg) and 2-phenylprop-2-yldithiobenzoate (5) (18.1 mg) in methyl methacrylate (1.6 g) was added asa single shot. Further 2-phenylprop-2-yl dithiobenzoate (5) (108 mg) inmethyl methacrylate (2.5 g) was then added over 10 minutes. A feed ofmethyl methacrylate (15 g) was commenced at a rate of 0.188 mL/min bysyringe pump. This was followed immediately by a feed of styrene (24 mL)at a rate of 0.2 mL/min. Further initiator (31.5 mg) was added every 90minutes during the feed periods. The reaction was held at 80° C. for afurther 120 minutes. The reaction mixture was sampled periodically toprovide samples for GPC analysis (see Table 37 below).

TABLE 37 Molecular weight and conversion data for poly(methylmethacrylate) and poly(methyl methacrylate-block-styrene) prepared with2-phenylprop-2-yl dithiobenzoate (5) at 80° C. in emulsion % M_(n) EntrySample M_(n) M_(w) M_(w)/M_(n) Conv (calc) 1 +7.5 g MMA  9 350 11 4301.22 43  9 430 2  +15 g MMA 25 000 38 600 1.54 85 31 022 3   +6 mLstyrene 36 000 61 000 1.68 >99 46 790 4  +12 mL styrene 49 000 92 0001.86 >99 57 171 5  +18 mL styrene 52 000 107 000  2.06 >99 67 552 6  +24mL styrene 72 000 162 000  2.24 >99 77 553 7 Final 72 000 159 000 2.21 >99 77 553

The use of GPC equipped with both a diode array detector and arefractive index detector provides evidence of block formation andpurity. Polymers with dithiobenzoate end groups have a strong absorptionin the region 300-330 nm (exact position depends on solvent andsubstituents). Neither polystyrene nor poly(methyl methacrylate) havesignificant absorption at this wavelength.

Example 77 Preparation of low polydispersity diblock poly(butylmethacrylate-block-styrene) via emulsion polymerisation at 80° C. in thepresence of 2-phenylprop-2-yl dithiobenzoate (5)

Water (52 g) and sodium dodecyl sulfate (0.55 g of 10% aqueous solution)were charged to 5-neck, 250 mL reactor fitted with a stirrer, condenserand thermocouple and degassed under nitrogen at 80° C. for 40 minutes. Asolution of 4,4′-azobis(4-cyanopentanoic acid) (71 mg) and2-phenylprop-2-yl dithiobenzoate (5) (17 mg) in butyl methacrylate (1.7g) was added as a single shot. Further 2-phenylprop-2-yl dithiobenzoate(5) (71 mg) in butyl methacrylate (2.7 g) was then added over 10minutes. Feeds of butyl methacrylate (16 g, 0.2485 mL/min) was thenadded by syringe pump. Further portions of 4,4′-azobis(4-cyanopentanoicacid) were added at 82 minutes (35 mg) and on completion of the monomerfeed at 142 minutes (20 mg). Feeds of styrene (15 g, 0.2 mL/min) and4,4′-azobis(4-cyanopentanoic acid) in water (38.7 g, 0.472 mL/min) werethen commenced. On completion of the feeds the reaction mixture was heldat 80° C. r a further 90 minutes. The reaction mixture was sampledperiodically for GPC analysis.

TABLE 38 Molecular weight and conversion data for poly(butylmethacrylate) and poly(butyl methacrylate-block-styrene) prepared withphenylprop-2-yl dithiobenzoate (5) at 80° C. in emulsion Entry SampleM_(n) M_(w) M_(w)/M_(n) % Conv M_(n) (calc) 1  +10.9 mL 26 000  39 0001.50 54 22 585 BMA 2 +16.01 g 63 000  77 000 1.22 95 57 742 BMA 3 final65 500  81 000 1.23 >99 60 876 4  +11.4 mL 70 500 115 000 1.63 84 91 846Styrene 5   +15 g 78 000 136 000 1.74 84 98 579 Styrene 6 Reaction 103000  177 000 1.73 >99 105 710  Final

Example 78 Preparation of low polydispersity poly(styrene-block-methylmethacrylate) by emulsion polymerization in the presence of benzyldithioacetate (12)

Water (50 g) and sodium dodecyl sulfate (3 g of 10% aqueous solution)were charged to a 5-neck reaction vessel equipped with a condenser,thermocouple, and mechanical stirrer. The mixture was heated at 80° C.for 40 minutes while purging with nitrogen. A solution of4,4′-azobis(4-cyanopentanoic acid) (87.5 mg) and benzyl dithioacetate(12) (104.2 mg) in styrene (2.3 g) was then added as a single shot.Feeds of styrene (13.6 g, 0.2 mL/min) and an initiator solution(4,4′-azobis(4-cyanopentanoic acid) (531 mg, 0.089 mL/min) in water (100g)) were commenced. On completion of the feeds the reaction temperaturewas increased to 90° C. and the addition of feeds of methyl methacrylate(15 mL, 0.316 mL/min) and 4,4′-azobis(4-cyanopentanoic acid) (265 mg) inwater (100 g) (0.312 mL/min) was commenced. After completion of thefeeds the reaction was held at 90° C. for a further 60 minutes. Thereaction mixture was sampled periodically for GPC analysis.

TABLE 39 Molecular weight and conversion data for poly(styrene) andpoly(methyl methacrylate-block-styrene) prepared with benzyldithioacetate in emulsion Entry Sample M_(n) M_(w) M_(w)/M_(n) % ConvM_(n) (calc) 1   +6 mL  7 690 10 500 1.37 43  4 560 styrene 2  +12 mL 22000 29 000 1.33 89  1 824 styrene 3  +15 mL 24 000 32 000 1.35 >99 25480 styrene 4 +7.5 mL 35 000 49 000 1.41 92 36 390 MMA 5  +15 mL 39 00061 000 1.56 84 45 513 MMA 6 Final 41 000 65 000 1.57 87 47 620The following two examples demonstrate the synthesis of narrowpolydispersity polymers by solution polymerization including a monomerfeed.

Example 79 Preparation of low polydispersity poly(n-butyl acrylate) bythe solution feed polymerization of butyl acrylate at 60° C. in thepresence of 1-phenylethyl dithiobenzoate (4)

n-Butyl acrylate (10 g), ethyl acetate (10 g), azobisisobutyronitrile(50 mg) and 1-phenylethyl dithiobenzoate (4) were placed in a 100 mL3-neck round bottom flask equipped with a condenser, mechanical stirrerand thermocouple, and degassed with nitrogen over 40 minutes withstirring. The flask was then placed in a pre-heated water bath at 60° C.After 60 minutes a solution of n-butyl acrylate (10 g) in ethyl acetate(5 g) was added over 3 hours (0.088 mL/min) by syringe pump. Oncompletion of the feed the reaction was held at 60° C. for a further 120minutes. The reaction mixture was sampled periodically for GPC analysis.

TABLE 40 Molecular weight and conversion data for poly(n-butyl acrylate)prepared with 1-phenylethyl dithiobenzoate (4) at 60° C. in ethylacetate Entry time/min M_(n) M_(w) M_(w)/M_(n) % Conv M_(n) (calc) 1 60 3 500  3 900 1.10 6.7  2 431 2 120  6 300  6 900 1.09 13.5  6 471 3 180 9 600 10 900 1.13 19.3 11 578 4 240 14 600 16 900 1.15 22.9 16 514 5300 18 800 23 000 1.20 34.6 24 955 6 300 21 700 25 800 1.19 45.0 32 410

Example 80 Preparation of low polydispersity poly(methyl methacrylate)by the solution feed polymerization of methyl methacrylate at 80° C. inthe presence of 2-phenylprop-2-yl Dithiobenzoate (5)

Methyl methacrylate (15 mL), 2-butanone (5 mL), azobisisobutyronitrile(20 mg) and 2-phenylprop-2-yl dithiobenzoate (5) (0.53 g) were placed ina 250 mL multi-neck round bottom flask equipped with a condenser,mechanical stirrer and thermocouple, and degassed with nitrogen over 40minutes with stirring. The mixture was then placed in a pre heated waterbath at 80° C. A solution of azobisisobutyronitrile (26.7 mg) in methylmethacrylate (40 mL) and 2-butanone (13.3 mL) was then added over 4hours (0.222 mL/min). On completion of the feed the reaction was held at80° C. for a further 90 minutes. The reaction mixture was sampledperiodically for GPC analysis.

TABLE 41 Molecular weight and conversion data for poly(methylmethacrylate) prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 60°C. in 2-butanone Entry time/min M_(n)  M_(w) M_(w)/M_(n) % Conv M_(n)(calc) 1  60 1 280 1 550 1.20 12.9 1 549 2 120 1 860 2 340 1.26 12.4 2085 3 180 2 900 3 730 1.28 23.5 5 074 4 240 4 100 5 200 1.27 32.0 8 4455 final 5 400 6 800 1.26 29.7 7 838

The following example demonstrates the effectiveness of dithioesters inproviding living characteristics in the suspension polymerization ofmethyl methacrylate. In order to achieve a low polydispersity themolecular weight must substantially smaller than the control molecularweight.

Example 81 Suspension polymerization of methyl methacrylate in thepresence of 2-phenylprop-2-yl dithiobenzoate

This example illustrates a suspension polymerization with VAZO® 64initiator and an ACRYLSOL® A1 polyacrylic acid suspension agent. Themolecular weight of the product is controlled with 2-phenylprop-2-yldithiobenzoate (5). The components employed are as follows where2-phenylprop-2-yl dithiobenzoate (5) is used at 0.10 by weight ofmonomer:

Parts by Weight Part 1 Deionized water 1490.39 ACRYLSOL ® A1 49.68Subtotal 1540.07 Part 2 methyl methacrylate 451.13 2-phenylprop-2-yldithiobenzoate 0.45 Subtotal 451.58 Part 3 VAZO ® 64 3.10 Deionizedwater 3.10 Subtotal 6.20 Final Total 1997.85

The initiator VAZO® 64 is commercially available from DuPont(Wilmington, Del.) and ACRYLSOL® A is commercially available from Rohm &Haas (Philadelphia, Pa.).

Into a jacketed flask with internal baffles and a high speed stirrer isadded methyl methacrylate monomer, a low molecular weight polyacrylicacid, and deionized water. The multi-bladed stirrer is engaged andincreased in speed to about 800 rpm. The contents of the flask areheated to 65° C. and the initiator is added. The contents are heated to80° C. and maintained at that temperature for two hours. The contents ofthe flask are filtered through cloth and washed with deionized water.The solid polymer is placed in an oven to dry. The reaction productobtained is 451.13 parts (23.41%) solids, the remainder being deionizedwater solvent.

TABLE 42 Molecular weight data for poly(methyl methacrylate) preparedwith 2-phenylprop-2-yl dithiobenzoate (5) by suspension polymerization2-phenylprop-2-yl dithiobenzoate (5) M_(n)/M_(w)/ Entry wt % M_(n) 1 082 000 3.75 2 0.10 52 000 2.01 3 0.50 26 500 2.13 4 1.00 16 200 1.31 5 082 800 3.70 6 0  9 300 3.76 7 1.00 14 900 1.52 8 1.00 15 500 1.30 9 2.00 9 150 1.24 10 2.00  9 490 1.30

Example 82 Polymerization of n-butyl acrylate in the presence of highconcentrations of 2-phenylprop-2-yl dithiobenzoate (5)

A stock solution of 1,1′-azobis(1-cyclohexanecarbonitrile) (15 mg) inn-butyl acrylate (30 g) and 2-butanone (30 g) was prepared. Aliquots (5mL) were placed in each of four ampoules and the required amounts ofstock solution of the dithioester (20 mg) in 2-butanone (0.55 mL) wereadded to give the concentrations indicated in Table 43. The samples weredegassed, sealed and heated at 80° C. for 60 minutes. The polymer formedwas isolated by evaporation and characterized by GPC.

TABLE 43 Molecular weight and conversion data for poly(n-butyl acrylate)prepared with 2-phenylprop-2-yl dithiobenzoate (5) at 80° C. in2-butanone Entry Dithioester [CTA] × 10⁻³ M M_(n) M_(w)/M_(n) Conv % 1(5) 0.74 67 000 1.84 40.2 2 (5) 1.54 52 000 1.56 38.4 3 (5) 2.94 30 0001.26 25.0 4 none 0 86 000 2.45 51.6The following two examples illustrate the effect of the nature of thedithioester on the extent of retardation observed when using highconcentrations of dithioester. The results demonstrate that the extentof retardation can be minimized by selecting a particular dithioesteraccording to the monomer being polymerized on the basis of theconsiderations discussed in the text.

Example 83 Polymerization of Styrene with various Dithioesters

A stock solution of 1,1′-azobis(1-cyclohexanecarbonitrile) (15 mg) instyrene (15 g) and toluene (15 g) was prepared. Aliquots (5 mL) wereplaced in each of four ampoules and the required amounts of a stocksolution of the appropriate dithioesters were added to give theconcentrations indicated in Table 44. The samples were degassed, sealedand heated at 111° C. for the times indicated in Table 44. The polymerformed was isolated by evaporation and characterized by GPC.

TABLE 44 Molecular weight and conversion data for polystyrene preparedwith various dithioesters at 110° C. in toluene time Conv [CTA] × EntryCTA (min) M_(n) M_(w)/M_(n) % 10−² M 1 2-cyanoprop-2-yl 60 2 330 1.0815.4 2.2 dithiobenzoate (15) 2 2-cyanoprop-2-yl 120 4 100 1.07 27.2 2.2dithiobenzoate (15) 3 2-phenylprop-2-yl 60 2 010 1.07 1.40 1.8dithiobenzoate (5) 4 2-phenylprop-2-yl 120 3 250 1.07 16.9 1.8dithiobenzoate (5) 5 none 60 62 000  1.57 21.3 0 6 none 120 68 000  1.6228.2 0

Example 84 Polymerizations of n-butyl acrylate with various Dithioesters

A stock solution of dimethyl 2,2′-azobisisobutyrate (7.5 mg) in n-butylacrylate (15 g) and 2-butanone (15 g) was prepared. Aliquots (5 mL) wereplaced in each of four ampoules and the required amounts of a stocksolution of the dithioester were added to give the concentrationsindicated in Table 45. The samples were degassed, sealed and heated at80° C. for the times indicated in Table 45. The polymer formed wasisolated by evaporation and characterized by GPC.

TABLE 45 Molecular weight and conversion data for poly(n-butyl acrylate)prepared with various dithioesters at 80° C. in in 2-butanone time Conv[CTA] × Entry CTA (min) M_(n) M_(w)/M_(n) % 10−² M 1 2-phenylprop-2-yl60   275 1.11 2.1 2.4 dithiobenzoate (5) 2 2-phenylprop-2-yl 120   5551.20 3.6 2.4 dithiobenzoate (5) 3 benzyl 60   790 1.16 3.2 2.6dithiobenzoate (3) 4 benzyl 120 1 397 1.21 7.3 2.6 dithiobenzoate (3) 5benzyl dithioacetate 60 3 550 1.18 25.1 3.4 (12) 6 benzyl dithioacetate120 6 100 1.17 49.8 3.4 (12) 7 none 60 76 000  2.63 67.8 0 8 none 120 89000  2.34 80.8 0The following two Examples demonstrate the use of the invention inmini-emulsion polymerization.

Example 85 Preparation of low polydispersity polystyrene viamini-emulsion polymerization with benzyl dithiobenzoate (3) at 70° C.

A 5-neck reaction vessel fitted with a stirrer, condenser andthermocouple was charged with water (75 g) and sodium dodecyl sulfate(215.2 mg), cetyl alcohol (53 mg), sodium bicarbonate (16.7 mg). Themixture was then homogenized for 10 minutes. Styrene (18.84 g) was addedand the mixture homogenized for a further 5 minutes. The reactionmixture was stirred (300 rpm) for 40 minutes while the temperature wasraised to 70° C. Benzyl dithiobenzoate (3) (107 mg) and2,2′-azobis(2-cyano-2-butane) (40.7 mg) were then added. The reactionmixture was heated at 70° C. with stirring (300 rpm) for 6 hours andsampled periodically for GPC analysis.

TABLE 46 Molecular weight and conversion data for polystyrene preparedwith benzyl dithiobenzoate (3) in mini-emulsion at 70° C. % Entrytime/min M_(n) M_(w)/M_(n) Conversion 1 60 2 080 1.78 7 2 120 2 980 1.2111 3 180 4 450 1.11 14 4 360 6 470 1.23 33A control experiment (no dithioester) gave M_(n) 480 000, M_(w)/M_(n)2.4, conversion 99% after 360 minutes.

Example 86 Preparation of low polydispersity polystyrene bymini-emulsion polymerization with benzyl dithiobenzoate (3) at 70° C.

An experiment carried out under conditions similar to those used forExample 85 but with potassium persulfate as initiator gave polystyreneM_(n) 6 770, M_(w)/M_(n) 1.15, conversion 26% after 360 minutes.

Example 87 Preparation of low polydispersity poly(ethylene oxide-blockstyrene)

A mixture of styrene (2.25 g) and dithioester (28) (0.14 g) was placedin an ampoule which was then degassed, sealed and heated at 110° C. for5.5 hours. The excess styrene was evaporated to give the title blockcopolymer with M_(n) 11 700 and M_(w)/M_(n) 1.4 at 27% conversion.Examination of the product by Gel permeation chromatography coupled withUV-Visible spectrophotometry established the presence of thedithiobenzoate end group in the final block copolymer.

Example 88 Preparation of low polydispersity poly(ethylene oxide-blockstyrene)

A mixture of styrene (4.5 g) and dithioester (29) (0.5 g) was placed inan ampoule which was then degassed, sealed and heated at 110° C. for 21hours. The excess styrene was evaporated to give the title blockcopolymer with M_(n) 7 800 and M_(w)/M_(n) 1.07 at 40% conversion.

1. A polymer of the Formula

wherein: Z is selected from the group consisting of hydrogen, chlorine,optionally substituted alkyl, optionally substituted aryl, optionallysubstituted heterocyclyl, optionally substituted alkylthio, optionallysubstituted alkoxycarbonyl or optionally substituted aryloxycarbonyl(—COOR″), carboxy (—COOH), optionally substituted acyloxy (—O₂CR″),optionally substituted carbamoyl (—CON R″₂), cyano (—CN), dialkyl- ordiaryl- phosphonato [—P(═O)(OR″)₂], dialkyl- or diaryl-phosphinato[—P(═O)R″₂], and a polymer chain formed by any mechanism; Z′ is am-valent moiety derived from a member of the group consisting ofoptionally substituted alkyl, optionally substituted aryl and a polymerchain; where the connecting moieties are selected from the group thatconsists of aliphatic carbon, aromatic carbon, and sulfur; Q is selectedfrom the group consisting of repeating unit

and repeating units from maleic anhydride, N-alkylmaleimide,N-arylmaleimide, dialkyl fumarate and cyclopolymerizable monomers; U isselected from the group consisting of hydrogen, halogen, optionallysubstituted C₁-C₄ alkyl, wherein the substituents are independentlyselected from the group consisting of hydroxy, alkoxy, aryloxy (OR″),carboxy, acyloxy, aroyloxy (O₂CR″), alkoxy-carbonyl and aryloxy-carbonyl(CO₂R″); V is selected from the group consisting of hydrogen, R″, CO₂H,CO₂R″, COR″, CN, CONH₂, CONHR″, CONR″₂, O₂CR″, OR″ and halogen; R isselected from the group consisting of optionally substituted alkyl; anoptionally substituted saturated, unsaturated or aromatic carbocyclic orheterocyclic ring; optionally substituted alkylthio; optionallysubstituted alkoxy; optionally substituted dialkylamino; anorganometallic species; and a polymer chain prepared by anypolymerization mechanism; R● being derived from a free radical leavinggroup that initiates free radical polymerization; R″ is selected fromthe group consisting of optionally substituted C₁-C₁₈ alkyl, C₂-C₁₈alkenyl, aryl, heterocyclyl, aralkyl, alkaryl wherein the substituentsare independently selected from the group that consists of epoxy,hydroxy, alkoxy, acyl, acyloxy, carboxy and carboxylates, sulfonic acidand sulfonates, alkoxy- or aryloxy- carbonyl, isocyanato, cyano, silyl,halo, and dialkylamino; q is 1 or an integer greater than 1; p is 1 oran integer greater than 1; when p≧2, then R═R′; m is an integer ≧2; andR′ is a p-valent moiety derived from a member of the group consisting ofoptionally substituted alkyl, optionally substituted aryl and a polymerchain; where the connecting moieties are selected from the groupconsisting of aliphatic carbon, aromatic carbon, silicon, and sulfur;R′● being derived from a free radical leaving group that initiates freeradical polymerization.
 2. The polymer according to claim 1 selectedfrom the group consisting of random, block, graft, star and gradientcopolymer.
 3. The polymer according to claim 2 having end groupfunctionality.
 4. A polymer of the formula

made by a process comprising contacting: (i) one or more monomersselected from the group consisting of vinyl monomers of structureCH₂═CUV, maleic anhydride, N-alkylmaleimide, N-arylmaleimide, dialkylfumarate and cyclopolymerizable monomers; (ii) a thiocarbonylthiocompound selected from the group consisting of:

having a chain transfer constant greater than about 0.1; and (iii) freeradicals produced from a free radical; and controlling thepolydispersity of the polymer being formed by varying the ratio of thenumber of molecules of (ii) to the number of molecules of (iii); thepolymer of Formula A being made by contacting (i), (ii)C and (iii) andthe polymer of Formula B being made by contacting (i), (ii) D and (iii);wherein: Z is selected from the group consisting of hydrogen, chlorine,optionally substituted alkyl, optionally substituted aryl, optionallysubstituted heterocycly, optionally substituted alkylthio, optionallysubstituted alkoxycarbonyl, optionally substituted aryloxycarbonyl(—COOR″), carboxy (—COOH), optionally substituted acyloxy (—O₂CR″),optionally substituted carbamoyl (—CONR″₂) cyano (—CN), dialkyl- ordialkyl- phoshonato [—P(═O)(OR″)₂], dialkyl- or diaryl-phosphinato[—P(═O)R″₂], and a polymer chain formed by any mechanism; Z′ is am-valent moiety derived from a member of the group consisting ofoptionally substituted alkyl, optionally substituted and a polymerchain; where the connecting moieties are selected from the group thatconsists of aliphatic carbon, aromatic carbon and sulfur; Q is selectedfrom the group consisting of repeating unit

repeating units from maleic anhydride, N-alkylmaleimide,N-arylmaleimide, dialkyl fumarate and cyclopolymerizable monomers; U isselected from the group consisting of hydrogen, halogen, optionallysubstituted C₁-C₄ alkyl wherein the substituents are independentlyselected from the group that consists of hydroxy, alkoxy, aryloxy (OR″),carboxy, acyloxy, aroyloxy (O₂CR″), alkoly- carbonyl and arloxy-carbonyl(CO₂R″); V is selected from the group consisting of hydrogen, R″, CO₂H,CO₂R″, COR″, CN, CONH₂, CONHR″, CONR″₂, O₂CR″, and halogen; R isselected from the group consisting of optionally substituted alkly; anoptionally substituted saturated unsaturated or aromatic carbocyclic orheterocyclic ring; optionally substituted alkylthio; optionallysubstituted alkoxy; optionally substituted dialkylamino; anorganometallic species; and a polymer chain prepared by anypolymerization mechanism; in compounds C and D, R. is a free-radicalleaving group that initiates free radical polymerization; R″ is selectedfrom the group consisting of optionally substituted C₁-C₁₈ alkyl, C₂-C₁₈alkenyl, aryl, wherein the substituents are independently selected fromthe group that consists of epoxy, hydroxy, alkoxy, acyl, acyloxy,carboxy and carboxylates, sulfonic acid and sulfonates, alkoxy- oraryloxy-carbonyl, isocyanato, cyano, silyl, halo, and dialkylamino; q is1 or an integer greater than 1; p is 1 an integer greater than 1; whenp≧2 then R=R′; m is an integer ≧2; and R′ is a p-valent moiety selectedfrom a member of the group consisting of optionally substituted alkyl,optionally substituted alkyl and a polymer chain; where the connectingmoieties are selected from the group consisting of aliphatic carbonaromatic carbon, silicon, and sulfur; in compounds C, R″. is a freeradical leaving group that initiates free radical polymerization.
 5. Asolution or emulsion of said polymer of the formula A or B of claim 4.6. A coating composition, compatibiliser, thermoplastic elastomer,dispersing agent, rheology control agent, photoresist, engineeringplastic, adhesive, or a sealant comprising said polymers of claim
 4. 7.A coating composition comprising said polymers of claim
 4. 8. Thecoating composition of claim 7 comprising pigments, durability agents,corrosion and oxidation inhibitors, rheology control agents, or metallicflakes.
 9. The coating composition of claim 7 or 8 wherein saidcomposition is suitable for producing clear coats or paints forautomobile or maintenance finishes.
 10. A composition comprisingpolymers of claim
 1. 11. The composition of claim 10 wherein saidcomposition is a coating composition, compatibiliser, thermoplasticelastomer, dispersing agent, rheology control agent, photoresist,engineering plastic, adhesive, or a sealant.
 12. The polymers of claim 1wherein Q results from styrene and butadiene monomers.
 13. A compositioncomprising the polymers of claim 12.